Edgar Filing: Interactive Brokers Group, Inc.

ibkr-s8pos.htm

As filed with the Securities and Exchange Commission on October 13, 2015

Registration Statement Nos. 333-142686, 333-174913 and 333-203358

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

___________________________

Post-Effective Amendment No. 1

FORM S-8

REGISTRATION STATEMENT UNDER

THE SECURITIES ACT OF 1933

___________________________

Interactive Brokers Group, Inc.

(Exact name of registrant as specified in its charter)

Delaware		30-0390693
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification Number)

One Pickwick Plaza

Greenwich, Connecticut 06830

(203) 618-5800

(Address, including zip code, and telephone number,

including area code, of registrant’s principal executive offices)

___________________________

Paul J. Brody

Chief Financial Officer

One Pickwick Plaza

Greenwich, Connecticut 06830

(203) 618-5800

(Name, address, including zip code, and telephone number,

including area code, of agent for service)

___________________________

With copies to:

Richard Goldberg, Esq.

Dechert LLP

1095 Avenue of the Americas

New York, New York 10036

(212) 698-3500

___________________________

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large accelerated filerý	Accelerated filer£
Non-accelerated filer£ (Do not check if a Smaller Reporting Company)	Smaller Reporting Company£

___________________________

CALCULATION OF REGISTRATION FEE


		Proposed Maximum	Proposed Maximum	Amount of
Title of Each Class of	Amount to be	Offering	Aggregate	Registration
Securities to be Registered	Registered (1)	Price per Unit (1)	Offering Price (1)	Fee (1)

Class A Common Stock, $0.01 par value per share	—	—	—	—

(1)

This Post-Effective Amendment No. 1 to Registration Statement No. 333-142686, Registration Statement No. 333-174913 and Registration Statement No. 333-203358 does not register any additional shares. This Post-Effective Amendment No. 1 pertains to the 9,200,000 shares registered on Form S-8 Registration Statement No. 333-142686, 10,800,000 shares registered on Form S-8 Registration Statement No. 333-174913 and the 10,000,000 shares registered on Form S-8 Registration Statement No. 333-203358. The filing fees for the 30,000,000 shares those registrations cover were paid when the registration statements were filed on May 7, 2007, June 15, 2011 and April 10, 2015, respectively.

EXPLANATORY NOTES

Interactive Brokers Group, Inc. (the “Company”) filed multiple Registration Statements under the Securities Act of 1933, as amended (the “Securities Act”) on Form S-8 to register shares of the Company’s Class A common stock, $0.01 par value, for issuance under the Company’s 2007 Stock Incentive Plan (the “Plan”): Registration No. 333-142686, filed on May 7, 2007 registering 9,200,000 shares; Registration No. 333-174913, filed on June 15, 2011, registering an additional 10,800,000 shares; and Registration No. 333-203358, filed on April 10, 2015 registering an additional 10,000,000 shares. Pursuant to General Instruction E of Form S-8, this Registration Statement incorporates by reference the contents of our Registration Statements on Form S-8 (Registration Nos. 333-142686, 333-174913 and 333-203358), except as otherwise set forth herein.

This Registration Statement includes a reoffer prospectus in Part I (the “Reoffer Prospectus”), which has been prepared in accordance with General Instruction C of Form S-8 and the requirements of Part I of Form S-3. The Reoffer Prospectus may be used for reoffers of shares of common stock (acquired or to be acquired pursuant to awards granted under the Plan) that are defined as “control securities” or “restricted securities” under General Instruction C of Form S-8.

In this reoffer prospectus, unless otherwise indicated or the context otherwise requires, the terms “IBG, Inc.,” “we,” “our,” “Company,” “issuer,” or “us” refer to Interactive Brokers Group, Inc. and its subsidiaries.

REOFFER PROSPECTUS

Common Stock

Interactive Brokers Group, Inc.

This reoffer prospectus relates to the reoffer and resale of up to 6,400,000 shares of Class A common stock, par value $0.01 per share of Interactive Brokers Group, Inc. which we sometimes refer to as the “Company.” The shares of Class A common stock, which we sometimes refer to as “shares” or “common stock”, are issuable pursuant to the terms of our 2007 Stock Incentive Plan as amended, which we refer to as the “Plan.” The shares may be offered for sale from time to time by IBG LLC (the “Selling Stockholder”), which has acquired or in some cases may hereafter acquire shares under the Plan, as described below under the caption “Selling Stockholder”.

The Plan provides employees with two options to pay for their withholding tax obligations, which become due when shares vest: either (1) reimburse the Company via cash payment, or (2) elect to have the Selling Stockholder withhold a portion of the vesting shares. In the case of employees who elect to have the Selling Stockholder withhold shares to cover their tax obligations, those shares are transferred to the Selling Stockholder. The Selling Stockholder, in turn, sells those shares in open market transactions to recover the amount paid to the tax authorities on the employees’ behalf. The number of shares covered by this reoffer prospectus represents the Company’s estimate of shares that will be withheld from employees related to the vesting of Plan shares over the next nine years based on current tax rates and historical employee elections. See “Selling Stockholders” beginning on page 13.

This reoffer prospectus has been prepared for the purpose of registering the shares under the Securities Act of 1933, as amended, which we refer to as the “Securities Act”, to allow for future sales by the Selling Stockholder, on a continuous or delayed basis, to the public without restriction. The Selling Stockholder may be deemed to be an “underwriter” within the meaning of the Securities Act. Any commissions received by a broker or dealer in connection with resales of shares may be deemed to be underwriting commissions or discounts under the Securities Act.

You should carefully read this reoffer prospectus, including the information it incorporates by reference before making a decision to purchase IBG, Inc.’s Class A common stock from the Selling Stockholder. The shares of common stock registered hereby may be sold from time to time directly by, or on behalf of, the Selling Stockholder in one or more transactions on the NASDAQ Stock Exchange Global Select Market® or on any other stock exchange on which our common stock may be listed at the time of sale, in privately negotiated transactions, or through a combination of such methods, at market prices prevailing at the time of sale, at prices related to such prevailing market prices, at fixed prices (which may be changed) or at negotiated prices.

Our Class A common stock is quoted on the NASDAQ Global Select Market under the symbol “IBKR”. On October 9, 2015, the last reported sale price for our Class A common stock was $38.95. Our principal executive office is located at One Pickwick Plaza, Greenwich Connecticut 06830. Our telephone number is (203) 618-5800.

Investing in our securities involves a high degree of risk. See “Risk Factors” beginning on Page 2 for information that you should consider before investing in our securities.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is October 13, 2015

TABLE OF CONTENTS

	Page
ABOUT THIS PROSPECTUS	1
ABOUT INTERACTIVE BROKERS GROUP, INC.	1
RISK FACTORS	2
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS	12
USE OF PROCEEDS	13
SELLING STOCKHOLDERS	13
PLAN OF DISTRIBUTION	14
DESCRIPTION OF CAPITAL STOCK	15
WHERE YOU CAN FIND MORE INFORMATION	18
INFORMATION INCORPORATED BY REFERENCE	18
LEGAL MATTERS	19
EXPERTS	19

-i-

ABOUT THIS PROSPECTUS

This reoffer prospectus provides you with a general description of the shares of Class A common stock we may offer. You should carefully read both this reoffer prospectus together with additional information described under the heading “Where You Can Find More Information” before making an investment decision.

We have not authorized any person to give any information or to make any representation in connection with this offering other than those contained or incorporated by reference in this reoffer prospectus, and, if given or made, such information or representation must not be relied upon as having been so authorized. This reoffer prospectus does not constitute an offer to sell or a solicitation of an offer to buy by anyone in any jurisdiction in which such offer to sell is not authorized, or in which the person is not qualified to do so or to any person to whom it is unlawful to make such offer or solicitation. Neither the delivery of this reoffer prospectus, nor any sale hereunder and thereunder shall, under any circumstances, create any implication that there has been no change in our affairs subsequent to the date set forth on the front of such document, that the information contained herein is correct as of any time subsequent to the date set forth on the front of such document, or that any information incorporated by reference is correct as of any time subsequent to the date set forth on the front of such document.

Any statement made in this reoffer prospectus or in a document incorporated or deemed to be incorporated by reference in this reoffer prospectus will be deemed to be modified or superseded for purposes of this reoffer prospectus to the extent that a statement contained in any other subsequently filed document that also is incorporated or deemed to be incorporated by reference in this reoffer prospectus modifies or supersedes that statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus. See “Information Incorporated by Reference” in this reoffer prospectus.

ABOUT INTERACTIVE BROKERS GROUP, INC.

IBG, Inc. is an automated global electronic broker and market maker specializing in executing and clearing trades in securities, futures, foreign exchange instruments, bonds and mutual funds on more than 100 electronic exchanges and trading venues around the world and offering custody, prime brokerage, stock and margin borrowing services to our customers. In the United States (“U.S.”), our business is conducted from our headquarters in Greenwich, Connecticut, and from Chicago, Illinois and Jersey City, New Jersey. Abroad, we conduct business through offices located in Canada, England, Switzerland, Liechtenstein, China (Hong Kong and Shanghai), India, Australia, and Japan.

IBG, Inc. is a holding company and our primary assets are our ownership of approximately 15.7% of the membership interests of IBG LLC, the current holding company for our businesses. The remaining approximately 84.3% of IBG LLC membership interests are held by IBG Holdings LLC (“Holdings”), a holding company that is owned by our founder, Chairman and Chief Executive Officer, Mr. Thomas Peterffy, and his affiliates, management and other employees of the Company, and certain other members. We are the sole managing member of IBG LLC. On May 3, 2007, IBG, Inc. priced its initial public offering (“IPO”) of shares of common stock. In connection with the IPO, IBG, Inc. purchased 10.0% of the membership interests in IBG LLC and began to consolidate IBG LLC’s financial results into its financial statements.

We are a successor to the market making business founded by our Chairman and Chief Executive Officer, Mr. Thomas Peterffy, on the floor of the American Stock Exchange in 1977. Since our inception, we have focused on developing proprietary software to automate broker-dealer functions. During that time, we have been a pioneer in developing and applying technology as a financial intermediary to increase liquidity and transparency in the capital markets in which we operate. The advent and evolution of electronic exchanges over the last 25 years has provided us with the opportunity to integrate our software with an increasing number of exchanges and trading venues into one automatically functioning, computerized platform that requires minimal human intervention. Developing our automated market making platform and our automation of many middle and back office functions for more than three decades has allowed us to become one of the lowest cost providers of broker-dealer services and significantly increase the volume of trades we handle.

Our activities are divided into two principal business segments: (1) electronic brokerage and (2) market making:

As a direct market access broker, we serve the customers of both traditional brokers and prime brokers. We provide our customers with an advanced order management, trade execution and portfolio management platform at a very low cost. Our customers can simultaneously access many financial markets worldwide and trade across multiple asset classes (stocks, options, futures, foreign exchange (“forex”), bonds and mutual funds) denominated in 21 different currencies, on one screen, from a single account based in any major currency. Our large bank and broker-dealer customers may “white label” our trading interface (i.e., make our trading interface available to their customers without referencing our name), or they can select from among our modular functionalities, such as order routing, trade reporting or clearing on specific products or exchanges where they may not have up-to-date technology, to offer their customers a comprehensive, global range of services and products. The emerging complexity of multiple trading venues provided us with the opportunity of building and continuously adapting our order routing software to secure excellent execution prices. This has become our major focus.

As a market maker, we provide continuous bid and offer quotations on over one million securities and futures products listed on electronic exchanges around the world. Our quotes are driven by proprietary mathematical models that assimilate market data and reevaluate our outstanding quotes each second. Unlike firms that trade over-the-counter (“OTC”) derivative products, our business creates liquidity and transparency on electronic exchanges. In the past several years our market making business has suffered from competitive pressures and along with the rapid increase of our brokerage business, its significance has diminished.

Our electronic brokerage and market making businesses are complementary. Both benefit from our combined scale and volume, as well as from our proprietary technology. Our brokerage customers benefit from the technology and market structure expertise developed in our market making business. The expense of developing and maintaining our unique technology, clearing, settlement, banking and regulatory structure required by any specific exchange or market center is shared by both of our businesses. These economies, in turn, enable us to provide lower transaction costs to our customers than our competitors. In addition, we believe we gain a competitive advantage by applying the software features we have developed for a specific product or market to newly-introduced products and markets over others who may have less automated facilities in one or both of our businesses or who operate only in a subset of the exchanges and market centers on which we operate. Our trading system contains unique architectural aspects that, together with our massive trading volume in markets worldwide, may impose a significant barrier to entry for firms wishing to compete in our specific businesses and permit us to compete favorably against our competitors.

RISK FACTORS

Any investment in our common stock involves a high degree of risk. You should carefully consider, among other things, the matters discussed under "Risk Factors" in our Annual Report on Form 10-K for the year ended December 31, 2014 as well as the other information incorporated by reference in this reoffer prospectus. The risks and uncertainties described in our Annual Report are not the only risks and uncertainties we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our business operations. If any of the following risks actually occur, our business, financial condition and results of operations could suffer. As a result, the trading price of our shares of common stock could decline, perhaps significantly, and you could lose all or part of your investment in the common stock. The risks discussed in our Annual Report also include forward-looking statements and our actual results may differ substantially from those discussed in these forward-looking statements. See "Cautionary Note Regarding Forward-Looking Statements.”

Certain Risks Related to Our Business

Our business may be harmed by global events beyond our control, including overall slowdowns in securities trading.

Like other brokerage and financial services firms, our business and profitability are directly affected by elements that are beyond our control, such as economic and political conditions, broad trends in business and finance, changes in volume of securities and futures transactions, changes in the markets in which such transactions occur and changes in how such transactions are processed. A weakness in equity markets, such as a slowdown causing reduction in trading volume in U.S. or foreign securities and derivatives, has historically resulted in reduced transaction revenues and would have a material adverse effect on our business, financial condition and results of operations.

Because our revenues and profitability depend on trading volume, they are prone to significant fluctuations and are difficult to predict.

Our revenues are dependent on the level of trading activity on securities and derivatives exchanges in the U.S. and abroad. In the past, our revenues and operating results have varied significantly from period to period due primarily to the willingness of competitors to trade more aggressively by decreasing their bid/offer spreads and thereby assuming more risk in order to acquire market share, to movements and trends in the underlying markets, and to fluctuations in trading levels. As a result, period to period comparisons of our revenues and operating results may not be meaningful, and future revenues and profitability may be subject to significant fluctuations or declines.

Our reliance on our computer software could cause us great financial harm in the event of any disruption or corruption of our computer software. We may experience technology failures while developing our software.

We rely on our computer software to receive and properly process internal and external data. Any disruption for any reason in the proper functioning or any corruption of our software or erroneous or corrupted data may cause us to make erroneous trades or suspend our services and could cause us great financial harm. To maintain our competitive advantage, our software is under continuous development. As we identify and enhance our software, there is risk that software failures may occur and result in service interruptions and have other unintended consequences.

Our business could be harmed by a systemic market event.

Some market participants could be overleveraged. In case of sudden, large price movements, such market participants may not be able to meet their obligations to brokers who, in turn, may not be able to meet their obligations to their counterparties. As a result, the financial system or a portion thereof could collapse, and the impact of such an event could be catastrophic to our business.

We may incur material trading losses from our market making activities.

A substantial portion of our revenues and operating profits is derived from our trading as principal in our role as a market maker and specialist. We may incur trading losses relating to these activities since each primarily involves the purchase or sale of securities for our own account. In any period, we may incur trading losses in a significant number of securities for a variety of reasons including:

•

price changes in securities;

•

lack of liquidity in securities in which we have positions; and

•

the required performance of our market making and specialist obligations.

These risks may limit or restrict our ability to either resell securities we purchased or to repurchase securities we sold. In addition, we may experience difficulty borrowing securities to make delivery to purchasers to whom we sold short, or lenders from whom we have borrowed. From time to time, we have large position concentrations in securities of a single issuer or issuers engaged in a specific industry or traded in a particular market. Such a concentration could result in higher trading losses than would occur if our positions and activities were less concentrated.

In our role as a market maker, we attempt to derive a profit from the difference between the prices at which we buy and sell, or sell and buy, securities. However, competitive forces often require us to match the quotes other market makers display and to hold varying amounts of securities in inventory. By having to maintain inventory positions, we are subjected to a high degree of risk. We cannot assure you that we will be able to manage such risk successfully or that we will not experience significant losses from such activities, which could have a material adverse effect on our business, financial condition and operating results.

Reduced spreads in securities pricing, levels of trading activity and trading through market makers and/or specialists could harm our business.

Computer-generated buy/sell programs and other technological advances and regulatory changes in the marketplace may continue to tighten spreads on securities transactions. Tighter spreads and increased competition could make the execution of trades and market making activities less profitable. In addition, new and enhanced alternative trading systems such as ECNs have emerged as an alternative for individual and institutional investors, as well as broker-dealers, to avoid directing their trades through market makers, and could result in reduced revenues derived from our market making business.

We may incur losses in our market making activities in the event of failures of our proprietary pricing model.

The success of our market making business is substantially dependent on the accuracy of our proprietary pricing mathematical model, which continuously evaluates and monitors the risks inherent in our portfolio, assimilates market data and reevaluates our outstanding quotes each second. Our model is designed to automatically rebalance our positions throughout the trading day to manage risk exposures on our positions in options, futures and the underlying securities. In the event of a flaw in our pricing model and/or a failure in the related software, our pricing model may lead to unexpected and/or unprofitable trades, which may result in material trading losses.

The valuation of the financial instruments we hold may result in large and occasionally anomalous swings in the value of our positions and in our earnings in any period.

The market prices of our long and short positions are reflected on our books at closing prices which are typically the last trade price before the official close of the primary exchange on which each such security trades. Given that we manage a globally integrated portfolio, we may have large and substantially offsetting positions in securities that trade on different exchanges that close at different times of the trading day. As a result, there may be large and occasionally anomalous swings in the value of our positions daily and, accordingly, in our earnings in any period. This is especially true on the last business day of each calendar quarter.

We are exposed to losses due to lack of perfect information.

As market makers, we provide liquidity by buying from sellers and selling to buyers. Quite often, we trade with others who have different information than we do, and as a result, we may accumulate unfavorable positions preceding large price movements in companies. Should the frequency or magnitude of these events increase, our losses will likely increase correspondingly.

Rules governing specialists and designated market makers may require us to make unprofitable trades or prevent us from making profitable trades.

Specialists and designated market makers are granted certain rights and have certain obligations to “make a market” in a particular security. They agree to specific obligations to maintain a fair and orderly market. In acting as a specialist or designated market maker, we are subjected to a high degree of risk by having to support an orderly market. In this role, we may at times be required to make trades that adversely affect our profitability. In addition, we may at times be unable to trade for our own account in circumstances in which it may be to our advantage to trade, and we may be obligated to act as a principal when buyers or sellers outnumber each other. In those instances, we may take a position counter to the market, buying or selling securities to support an orderly market. Additionally, the rules of the markets, which govern our activities as a specialist or designated market maker, are subject to change. If these rules are made more stringent, our trading revenues and profits as specialist or designated market maker could be adversely affected.

We are subject to potential losses as a result of our clearing and execution activities.

As a clearing member firm providing financing services to certain of our brokerage customers, we are ultimately responsible for their financial performance in connection with various stock, options and futures transactions. Our clearing operations require a commitment of our capital and, despite safeguards implemented by our software, involve risks of losses due to the potential failure of our customers to perform their obligations under these transactions. If our customers default on their obligations, we remain financially liable for such obligations, and although these obligations are collateralized, we are subject to market risk in the liquidation of customer collateral to satisfy those obligations. There can be no assurance that our risk management procedures will be adequate. Any liability arising from clearing operations could have a material adverse effect on our business, financial condition and/or operating results.

As a clearing member firm of securities and commodities clearing houses in the U.S. and abroad, we are also exposed to clearing member credit risk. Securities and commodities clearing houses require member firms to deposit cash and/or government securities to a clearing fund. If a clearing member defaults in its obligations to the clearing house in an amount larger than its own margin and clearing fund deposits, the shortfall is absorbed pro rata from the deposits of the other clearing members. Many clearing houses of which we are members also have the authority to assess their members for additional funds if the clearing fund is depleted. A large clearing member default could result in a substantial cost to us if we are required to pay such assessments.

We may not pay dividends on our common stock at any time in the foreseeable future.

As a holding company for our interest in IBG LLC we will be dependent upon the ability of IBG LLC to generate earnings and cash flows and distribute them to us so that we may pay any dividends to our stockholders. To the extent (if any) that we have excess cash, any decision to declare and pay dividends in the future will be made at the discretion of our board of directors and will depend on, among other things, our results of operations, financial conditions, cash requirement, contractual restrictions and other factors that our board of directors may deem relevant. In December 2010 and December 2012, special cash dividends were paid to holders of our common stock. Since the second quarter of 2011, the Company has declared and paid a quarterly cash dividend of $0.10 per share. Although not required, we currently intend to pay quarterly dividends of $0.10 per share to our common stockholders for the foreseeable future.

Regulatory and legal uncertainties could harm our business.

The securities and derivatives businesses are heavily regulated. Firms in financial service industries have been subject to an increasingly regulated environment over recent years, and penalties and fines sought by regulatory authorities have increased accordingly. This regulatory and enforcement environment has created uncertainty with respect to various types of transactions that historically had been entered into by financial services firms and that were generally believed to be permissible and appropriate. Our broker-dealer subsidiaries are subject to regulations in the United States (“U.S.”) and abroad covering all aspects of their business. Regulatory bodies include, in the U.S., the Securities Exchange Commission (“SEC”), Financial Industry Regulatory Authority (“FINRA”), the Board of Governors of the Federal Reserve System (“the Federal Reserve”), the Chicago Board Options Exchange, the Chicago Mercantile Exchange, the Commodity Futures Trading Commission (“CFTC”), and the National Futures Association; in Switzerland, the Swiss Financial Market Supervisory Authority; in the United Kingdom, the Financial Conduct Authority; in Hong Kong, the Securities and Futures Commission; in Australia, the Australian Securities and Investment Commission; in India, the Securities and Exchange Board of India; in Canada, the Investment Industry Regulatory Organization of Canada and various Canadian securities commissions; and in Japan, the Financial Supervisory Agency and the Japan Securities Dealers Association. Our mode of operation and profitability may be directly affected by additional legislation changes in rules promulgated by various domestic and foreign government agencies and self-regulatory organizations that oversee our businesses, and changes in the interpretation or enforcement of existing laws and rules, including the potential imposition of transaction taxes. Noncompliance with applicable laws or regulations could result in sanctions being levied against us, including fines and censures, suspension or expulsion from a certain jurisdiction or market or the revocation or limitation of licenses. Noncompliance with applicable laws or regulations could adversely affect our reputation, prospects, revenues and earnings. In addition, changes in current laws or regulations or in governmental policies could adversely affect our operations, revenues and earnings.

Domestic and foreign stock exchanges, other self-regulatory organizations and state and foreign securities commissions can censure, fine, issue cease-and-desist orders, suspend or expel a broker-dealer or any of its officers or employees. Our ability to comply with all applicable laws and rules is largely dependent on our internal system to ensure compliance, as well as our ability to attract and retain qualified compliance personnel. We could be subject to disciplinary or other actions in the future due to claimed noncompliance, which could have a material adverse effect on our business, financial condition and results of operations. To continue to operate and to expand our services internationally, we may have to comply with the regulatory controls of each country in which we conduct, or intend to conduct business, the requirements of which may not be clearly defined. The varying compliance requirements of these different regulatory jurisdictions, which are often unclear, may limit our ability to continue existing international operations and further expand internationally.

Our future efforts to sell shares or raise additional capital may be delayed or prohibited by regulations.

As certain of our subsidiaries are members of FINRA, we are subject to certain regulations regarding changes in control of our ownership. FINRA Rule 1017 generally provides that FINRA approval must be obtained in connection with any transaction resulting in a change in control of a member firm. FINRA defines control as ownership of 25% or more of the firm’s equity by a single entity or person and would include a change in control of a parent company. Interactive Brokers (U.K.) Limited is subject to similar change in control regulations promulgated by the Financial Conduct Authority in the United Kingdom. As a result of these regulations, our future efforts to sell shares or raise additional capital may be delayed or prohibited. We may be subject to similar restrictions in other jurisdictions in which we operate.

We depend on our proprietary technology, and our future results may be impacted if we cannot maintain technological superiority in our industry.

Our success in the past has largely been attributable to our sophisticated proprietary technology that has taken many years to develop. We have benefited from the fact that the type of proprietary technology equivalent to that which we employ has not been widely available to our competitors. If our technology becomes more widely available to our current or future competitors for any reason, our operating results may be adversely affected. Additionally, adoption or development of similar or more advanced technologies by our competitors may require that we devote substantial resources to the development of more advanced technology to remain competitive. The markets in which we compete are characterized by rapidly changing technology, evolving industry standards and changing trading systems, practices and techniques. Although we have been at the forefront of many of these developments in the past, we may not be able to keep up with these rapid changes in the future, develop new technology, realize a return on amounts invested in developing new technologies or remain competitive in the future.

The loss of our key employees would materially adversely affect our business.

Our key executives have substantial experience and have made significant contributions to our business, and our continued success is dependent upon the retention of our key management executives, as well as the services provided by our staff of trading system, technology and programming specialists and a number of other key managerial, marketing, planning, financial, technical and operations personnel. The loss of such key personnel could have a material adverse effect on our business. Growth in our business is dependent, to a large degree, on our ability to retain and attract such employees.

We are exposed to risks associated with our international operations.

During the first six months of 2015, approximately 32% of our net revenues were generated by our operating companies outside the U.S. We are exposed to risks and uncertainties inherent in doing business in international markets, particularly in the heavily regulated brokerage industry. Such risks and uncertainties include political, economic and financial instability; unexpected changes in regulatory requirements, tariffs and other trade barriers; exchange rate fluctuations; applicable currency controls; and difficulties in staffing, including reliance on newly hired local experts, and managing foreign operations. These risks could cause a material adverse effect on our business, financial condition or results of operations.

We do not have fully redundant systems. System failures could harm our business.

If our systems fail to perform, we could experience unanticipated disruptions in operations, slower response times or decreased customer service and customer satisfaction. Our ability to facilitate transactions successfully and provide high quality customer service also depends on the efficient and uninterrupted operation of our computer and communications hardware and software systems. Our service has experienced periodic system interruptions, which we believe will continue to occur from time to time. Our systems and operations also are vulnerable to damage or interruption from human error, natural disasters, power loss, telecommunication failures, break-ins, sabotage, computer viruses, intentional acts of vandalism and similar events. While we currently maintain redundant servers to provide limited service during system disruptions, we do not have fully redundant systems, and our formal disaster recovery plan does not include restoration of all services. For example, we have backup facilities at our disaster recovery site that enable us, in the case of complete failure of our main North America data center, to recover and complete all pending transactions, provide customers with access to their accounts to deposit or withdraw money, transfer positions to other brokers and manage their risk by continuing trading through the use of marketable orders. These backup services are currently limited to U.S. markets. We do not currently have separate backup facilities dedicated to our non-U.S. operations. It is our intention to provide for and progressively deploy backup facilities for our global facilities over time. In addition, we do not carry business interruption insurance to compensate for losses that could occur to the extent not required. Any system failure that causes an interruption in our service or decreases the responsiveness of our service could impair our reputation, damage our brand name and materially adversely affect our business, financial condition and results of operations.

Failure of third-party systems on which we rely could adversely affect our business.

We rely on certain third-party computer systems or third-party service providers, including clearing systems, exchange systems, Internet service, communications facilities and other facilities. Any interruption in these third-party services, or deterioration in their performance, could be disruptive to our business. If our arrangement with any third party is terminated, we may not be able to find an alternative source of systems support on a timely basis or on commercially reasonable terms. This could have a material adverse effect on our business, financial condition and results of operations.

We face competition in our market making activities.

In our market making activities, we compete with other firms based on our ability to provide liquidity at competitive prices and to attract order flow. These firms include registered market makers as well as high frequency trading firms (“HFTs”) that act as market makers. Both types of competitors range from sole proprietors with very limited resources to a few highly sophisticated groups which have substantially greater financial and other resources, including research and development personnel, than we do. These larger and better capitalized competitors may be better able to respond to changes in the market making industry, to compete for skilled professionals, to finance acquisitions, to fund internal growth and to compete for market share generally. HFTs that are not registered market makers have certain advantages over registered market making firms that may allow them to bypass regulatory restrictions and trade more quickly and cheaply than registered market makers at some exchanges. We may not be able to compete effectively against HFTs or market makers with greater financial resources, and our failure to do so could materially and adversely affect our business, financial condition and results of operations. As in the past, we may in the future face enhanced competition, resulting in narrowing bid/offer spreads in the marketplace that may adversely impact our financial performance. This is especially likely if HFTs continue to receive advantages in capturing order flow or if others can acquire systems that enable them to predict markets or process trades more efficiently than we can.

Our direct market access clearing and non-clearing brokerage operations face intense competition.

With respect to our direct market access brokerage business, the market for electronic and interactive bidding, offering and trading services in connection with equities, options and futures is relatively new, rapidly evolving and intensely competitive. We expect competition to continue and intensify in the future. Our current and potential future competition principally comes from five categories of competitors:

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prime brokers who, in an effort to satisfy the demands of their customers for hands-on electronic trading facilities, universal access to markets, smart routing, better trading tools, lower commissions and financing rates, have embarked upon building such facilities and product enhancements;

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direct market access and online options and futures firms;

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direct market access and online equity brokers;

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software development firms and vendors who create global trading networks and analytical tools and make them available to brokers; and

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traditional brokers.

In addition, we compete with financial institutions, mutual fund sponsors and other organizations, many of which provide online, direct market access or other investing services. A number of brokers provide our technology and execution services to their customers, and these brokers will become our competitors if they develop their own technology. Some of our competitors in this area have greater name recognition, longer operating histories and significantly greater financial, technical, marketing and other resources than we have and offer a wider range of services and financial products than we do. Some of our competitors may also have an ability to charge lower commissions. We cannot assure you that we will be able to compete effectively or efficiently with current or future competitors. These increasing levels of competition in the online trading industry could significantly harm this aspect of our business.

We are subject to risks relating to litigation and potential securities laws liability.

We are exposed to substantial risks of liability under federal and state securities laws, other federal and state laws and court decisions, as well as rules and regulations promulgated by the SEC, the CFTC, the Federal Reserve, state securities regulators, the self-regulatory organizations and foreign regulatory agencies. We are also subject to the risk of litigation and claims that may be without merit. We could incur significant legal expenses in defending ourselves against and resolving lawsuits or claims. An adverse resolution of any future lawsuits or claims against us could result in a negative perception of our company and cause the market price of our common stock to decline or otherwise have an adverse effect on our business, financial condition and/or operating results.

Any future acquisitions may result in significant transaction expenses, integration and consolidation risks and risks associated with entering new markets, and we may be unable to profitably operate our consolidated company.

Although our growth strategy has not focused historically on acquisitions, we may in the future engage in evaluations of potential acquisitions and new businesses. We may not have the financial resources necessary to consummate any acquisitions in the future or the ability to obtain the necessary funds on satisfactory terms. Any future acquisitions may result in significant transaction expenses and risks associated with entering new markets in addition to integration and consolidation risks. Because acquisitions historically have not been a core part of our growth strategy, we have no material experience in successfully utilizing acquisitions. We may not have sufficient management, financial and other resources to integrate any such future acquisitions or to successfully operate new businesses and we may be unable to profitably operate our expanded company.

Internet-related issues may reduce or slow the growth in the use of our services in the future.

Critical issues concerning the commercial use of the Internet, such as ease of access, security, privacy, reliability, cost, and quality of service, remain unresolved and may adversely impact the growth of Internet use. If Internet usage continues to increase rapidly, the Internet infrastructure may not be able to support the demands placed on it by this growth, and its performance and reliability may decline. Although our larger institutional customers use leased data lines to communicate with us, our ability to increase the speed with which we provide services to consumers and to increase the scope and quality of such services is limited by and dependent upon the speed and reliability of our customers’ access to the Internet, which is beyond our control. If periods of decreased performance, outages or delays on the Internet occur frequently or other critical issues concerning the Internet are not resolved, overall Internet usage or usage of our web based products could increase more slowly or decline, which would cause our business, results of operations and financial condition to be materially and adversely affected.

Our computer infrastructure may be vulnerable to security breaches. Any such problems could jeopardize confidential information transmitted over the Internet, cause interruptions in our operations or cause us to have liability to third persons.

Our computer infrastructure is potentially vulnerable to physical or electronic computer break-ins, viruses and similar disruptive problems and security breaches. Any such problems or security breaches could cause us to have liability to one or more third parties, including our customers, and disrupt our operations. A party able to circumvent our security measures could misappropriate proprietary information or customer information, jeopardize the confidential nature of information transmitted over the Internet or cause interruptions in our operations. Concerns over the security of Internet transactions and the privacy of users could also inhibit the growth of the Internet or the electronic brokerage industry in general, particularly as a means of conducting commercial transactions. To the extent that our activities involve the storage and transmission of proprietary information such as personal financial information, security breaches could expose us to a risk of financial loss, litigation and other liabilities. Our estimated annual losses from reimbursements to customers whose accounts have been negatively affected by unauthorized access have historically been less than $500,000 annually, but instances of unauthorized access of customer accounts have been increasing recently on an industry-wide basis. Our current insurance program may protect us against some, but not all, of such losses. Any of these events, particularly if they (individually or in the aggregate) result in a loss of confidence in our company or electronic brokerage firms in general, could have a material adverse effect on our business, results of operations and financial condition.

We may not be able to protect our intellectual property rights or may be prevented from using intellectual property necessary for our business.

We rely primarily on trade secret, contract, copyright, patent and trademark laws to protect our proprietary technology. It is possible that third parties may copy or otherwise obtain and use our proprietary technology without authorization or otherwise infringe on our rights. We may also face claims of infringement that could interfere with our ability to use technology that is material to our business operations.

In the future, we may have to rely on litigation to enforce our intellectual property rights, protect our trade secrets, determine the validity and scope of the proprietary rights of others or defend against claims of infringement or invalidity. Any such litigation, whether successful or unsuccessful, could result in substantial costs and the diversion of resources and the attention of management, any of which could negatively affect our business.

Our future success will depend on our response to the demand for new services, products and technologies.

The demand for market making services, particularly services that rely on electronic communications gateways, is characterized by:

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rapid technological change;

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changing customer demands;

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the need to enhance existing services and products or introduce new services and products; and

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evolving industry standards.

New services, products and technologies may render our existing services, products and technologies less competitive. Our future success will depend, in part, on our ability to respond to the demand for new services, products and technologies on a timely and cost-effective basis and to adapt to technological advancements and changing standards to address the increasingly sophisticated requirements and varied needs of our customers and prospective customers. We cannot assure you that we will be successful in developing, introducing or marketing new services, products and technologies. In addition, we may experience difficulties that could delay or prevent the successful development, introduction or marketing of these services and products, and our new service and product enhancements may not achieve market acceptance. Any failure on our part to anticipate or respond adequately to technological advancements, customer requirements or changing industry standards, or any significant delays in the development, introduction or availability of new services, products or enhancements could have a material adverse effect on our business, financial condition and operating results.

Market making in forex-based products entails significant risk, and unforeseen events in such business could have an adverse effect on our business, financial condition and results of operation.

Our activities in market making for forex-based products include the trading of cash in foreign currencies with banks and exchange-listed futures, options on futures, options on cash deposits and currency-based ETFs. All of the risks that pertain to our market making activities in equity-based products also apply to our forex-based market making. In addition, we have comparatively less experience in the forex markets and even though we have expanded this activity slowly, any kind of unexpected event can occur that can result in great financial loss.

We are subject to counterparty risk whereby defaults by parties with whom we do business can have an adverse effect on our business, financial condition and/or operating results.

In our electronic brokerage business, our customer margin credit exposure is to a great extent mitigated by our policy of automatically evaluating each account throughout the trading day and closing out positions automatically for accounts that are found to be under-margined. While this methodology is effective in most situations, it may not be effective in situations in which no liquid market exists for the relevant securities or commodities or in which, for any reason, automatic liquidation for certain accounts has been disabled. If no liquid market exists or automatic liquidation has been disabled, we are subject to risks inherent in extending credit, especially during periods of rapidly declining markets. Any loss or expense incurred due to defaults by our customers in failing to repay margin loans or to maintain adequate collateral for these loans would cause harm to our business.

Certain Risks Related to Our Company Structure

Future sales of our common stock in the public market could lower our stock price, and any additional capital raised by us through the sale of equity or convertible securities may dilute your ownership in us.

The members of Holdings have the right to cause the redemption of their Holdings membership interests over time in connection with offerings of shares of our common stock. We intend to sell additional shares of common stock in public offerings in the future, which may include offerings of our common stock to finance future purchases of IBG LLC membership interests which, in turn, will finance corresponding redemptions of Holdings membership interests. These offerings and related transactions were anticipated to occur on or about each of the first eight years following the IPO. Given the absence of any public offering subsequent to our IPO in 2007 through 2010 (and the relatively minor amounts associated with the 2011 through 2015 redemptions) and depending on the timing of redemptions, this offering schedule has been extended into the future in accordance with the amended Exchange Agreement. The size and occurrence of these offerings may be affected by market conditions. We may also issue additional shares of common stock or convertible debt securities to finance future acquisitions or business combinations. We currently have approximately 63.4 million outstanding shares of common stock. Assuming no anti-dilution adjustments based on combinations or divisions of our common stock, the offerings referred to above could result in the issuance by us of up to an additional approximately 343.3 million shares of common stock. It is possible, however, that such shares could be issued in one or a few large transactions.

We cannot predict the size of future issuances of our common stock or the effect, if any, that future issuances and sales of shares of our common stock may have on the market price of our common stock. Sales of substantial amounts of our common stock (including shares issued in connection with an acquisition), or the perception that such sales could occur, may cause the market price of our common stock to decline.

Control by Mr. Thomas Peterffy of a majority of the combined voting power of our common stock may give rise to conflicts of interests and could discourage a change of control that other stockholders may favor, which could negatively affect our stock price, and adversely affect stockholders in other ways.

Mr. Thomas Peterffy, our founder, Chairman and Chief Executive Officer, and his affiliates beneficially own approximately 88.7% of the economic interests and all of the voting interests in Holdings, which owns all of our Class B common stock, representing approximately 84.3% of the combined voting power of all classes of our voting stock. As a result, Mr. Thomas Peterffy has the ability to elect all of the members of our board of directors and thereby to control our management and affairs, including determinations with respect to acquisitions, dispositions, material expansions or contractions of our business, entry into new lines of business, borrowings, issuances of common stock or other securities, and the declaration and payment of dividends on our common stock. In addition, Mr. Thomas Peterffy is able to determine the outcome of all matters requiring stockholder approval and will be able to cause or prevent a change of control of our company or a change in the composition of our board of directors and could preclude any unsolicited acquisition of our company. The concentration of ownership could discourage potential takeover attempts that other stockholders may favor and could deprive stockholders of an opportunity to receive a premium for their common stock as part of a sale of our company and this may adversely affect the market price of our common stock.

Moreover, because of Mr. Thomas Peterffy’s substantial ownership, we are eligible to be and are, treated as a “controlled company” for purposes of the NASDAQ Marketplace Rules. As a result, we are not required by NASDAQ to have a majority of independent directors or to maintain Compensation and Nominating and Corporate Governance Committees composed entirely of independent directors to continue to list the shares of our common stock on The NASDAQ Global Select Market (“NASDAQ GS”). Our Compensation Committee is comprised of Messrs. Thomas Peterffy (Chairman of the Compensation Committee) and Earl H. Nemser (our Vice Chairman). Mr. Thomas Peterffy’s membership on the Compensation Committee may give rise to conflicts of interests in that Mr. Thomas Peterffy is able to influence all matters relating to executive compensation, including his own compensation.

We are dependent on IBG LLC to distribute cash to us in amounts sufficient to pay our tax liabilities and other expenses.

We are a holding company and our primary assets are our approximately 15.7% equity interest in IBG LLC and our controlling interest and related rights as the sole managing member of IBG LLC and, as such, we operate and control all of the business and affairs of IBG LLC and are able to consolidate IBG LLC’s financial results into our financial statements. We have no independent means of generating revenues. IBG LLC is treated as a partnership for U.S. federal income tax purposes and, as such, is not subject to U.S. federal income tax. Instead, its taxable income is allocated on a pro rata basis to Holdings and us. Accordingly, we incur income taxes on our proportionate share of the net taxable income of IBG LLC, and also incur expenses related to our operations. We intend to cause IBG LLC to distribute cash to its members in amounts at least equal to that necessary to cover their tax liabilities, if any, with respect to the earnings of IBG LLC. To the extent we need funds to pay such taxes, or for any other purpose, and IBG LLC is unable to provide such funds, it could have a material adverse effect on our business, financial condition or results of operations.

We are required to pay Holdings for the benefit relating to additional tax depreciation or amortization deductions we claim as a result of the tax basis step-up our subsidiaries received in connection with our IPO and certain subsequent redemptions of Holdings membership interests.

In connection with our IPO, we purchased interests in IBG LLC from Holdings for cash. In August 2011, November 2013, October 2014 and July 2015, in connection with redemptions of Holdings membership interests, we acquired additional interests in IBG LLC by issuing shares of Class A common stock in exchange for an equivalent number of shares of member interests in IBG LLC (the “Redemptions”). In addition, IBG LLC membership interests held by Holdings may be sold in the future to us and financed by our issuances of shares of our common stock. The initial purchase and the Redemptions did, and subsequent purchases may, result in increases in the tax basis of the tangible and intangible assets of IBG LLC and its subsidiaries that otherwise would not have been available. Such increase will be approximately equal to the amount by which our stock price at the time of the purchase exceeds the income tax basis of the assets of IBG LLC underlying the IBG LLC interests acquired by us. These increases in tax basis will result in increased deductions in computing our taxable income and resulting tax savings for us generally over the 15 year period which commenced with the initial purchase. We have agreed to pay 85% of these tax savings, if any, to Holdings as they are realized as additional consideration for the IBG LLC interests that we acquire.

As a result of the IPO and the redemptions by Holdings, the increase in the tax basis attributable to our interest in IBG LLC is $1.17 billion. The tax savings that we would actually realize as a result of this increase in tax basis likely would be significantly less than this amount multiplied by our effective tax rate due to a number of factors, including the allocation of a portion of the increase in tax basis to foreign or non-depreciable fixed assets, the impact of the increase in the tax basis on our ability to use foreign tax credits and the rules relating to the amortization of intangible assets, for example. Based on the facts and assumptions at December 31, 2014, including that subsequent purchases of IBG LLC interests will occur in fully taxable transactions, the potential tax basis increase resulting from the historical and future purchases of the IBG LLC interests held by Holdings could be as much as $6.76 billion. The tax receivable agreement requires 85% of such tax savings, if any, to be paid to Holdings, with the balance to be retained by us. The actual increase in tax basis depends, among other factors, upon the price of shares of our common stock at the time of the purchase and the extent to which such purchases are taxable and, as a result, could differ materially from this amount. Our ability to achieve benefits from any such increase, and the amount of the payments to be made under the tax receivable agreement, depends upon a number of factors, as discussed above, including the timing and amount of our future income.

The tax basis of $6.76 billion assumes that (a) all remaining IBG LLC membership interests held by Holdings are purchased by the Company and (b) such purchases in the future are made at prices that reflect the closing share price at December 31, 2014. In order to have a $6.76 billion tax basis, the offering price per share of Class A common stock in such future public offering will need to exceed the then current cost basis per share of Class A common stock by approximately $16.39.

If either immediately before or immediately after any purchase or the related issuance of our stock, the Holdings members own or are deemed to own, in the aggregate, more than 20% of our outstanding stock, then all or part of any increase in the tax basis of

goodwill may not be amortizable and, thus, our ability to realize the annual tax savings that otherwise would have resulted if such tax basis were amortizable may be significantly reduced. Although the Holdings members are prohibited under the Exchange Agreement from purchasing shares of Class A common stock, grants of our stock to employees and directors who are also members or related to members of Holdings and the application of certain tax attribution rules, such as among family members and partners in a partnership, could result in Holdings members being deemed for tax purposes to own shares of Class A common stock.

If the Internal Revenue Service successfully challenges the tax basis increase, under certain circumstances, we could be required to make payments to Holdings under the tax receivable agreement in excess of our cash tax savings.

Certain provisions in our amended and restated certificate of incorporation may prevent efforts by our stockholders to change our direction or management.

Provisions contained in our amended and restated certificate of incorporation could make it more difficult for a third party to acquire us, even if doing so might be beneficial to our stockholders. For example, our amended and restated certificate of incorporation authorizes our board of directors to determine the rights, preferences, privileges and restrictions of unissued series of preferred stock, without any vote or action by our stockholders. We could issue a series of preferred stock that could impede the completion of a merger, tender offer or other takeover attempt. These provisions may discourage potential acquisition proposals and may delay, deter or prevent a change of control of us, including through transactions, and, in particular, unsolicited transactions, that some or all of our stockholders might consider to be desirable. As a result, efforts by our stockholders to change our direction or management may be unsuccessful.

Risks Related to the Offering

The market price of our common stock may fluctuate significantly, and this may make it difficult for holders to resell our common stock when they want or at prices that they find attractive.

The price of our common stock on the NASDAQ Global Select Market constantly changes. We expect that the market price of our common stock will continue to fluctuate. The market price of our common stock may fluctuate as a result of a variety of factors, many of which are beyond our control. These factors include:

changes in market conditions;

quarterly variations in our operating results;

operating results that vary from the expectations of management, securities analysts and investors;

changes in expectations as to our future financial performance;

announcements of strategic developments, significant contracts, acquisitions and other material events by us or our competitors;

the operating and securities price performance of other companies that investors believe are comparable to us;

future sales of our equity or equity-related securities;

changes in the economy and the financial markets;

departures of key personnel;

changes in governmental regulations; and

geopolitical conditions, such as acts or threats of terrorism or military conflicts.

In addition, in recent years, global equity markets have experienced extreme price and volume fluctuations. This volatility has had a significant effect on the market price of securities issued by many companies for reasons often unrelated to their operating performance. These broad market fluctuations may adversely affect the market price of our common stock, regardless of our operating results.

The common stock are equity interests and are subordinate to our existing and future indebtedness.

The common stock are equity interests. This means the common stock will rank junior to all of our indebtedness and to other non-equity claims on us and our assets available to satisfy claims on us, including claims in a bankruptcy or similar proceeding. Future indebtedness may restrict, payment of dividends on the common stock.

Additionally, unlike indebtedness, where principal and interest customarily are payable on specified due dates, in the case of common stock, (i) dividends are payable only when and if declared by our board of directors or a duly authorized committee of the board and (ii) as a corporation, we are restricted to only making dividend payments and redemption payments out of legally available assets. Further, the common stock places no restrictions on our business or operations or on our ability to incur indebtedness or engage in any transactions, subject only to the voting rights available to stockholders generally.

There may be future sales or issuances of our common stock, which will dilute the ownership interests of stockholders and may adversely affect the market price of our common stock.

We may issue additional common stock, including securities that are convertible into or exchangeable for, or that represent the right to receive, common stock or substantially similar securities, which may result in dilution to our stockholders. In addition, our stockholders may be further diluted by future issuances under our equity incentive plans. The market price of our common stock could decline as a result of sales or issuances of a large number of our common stock or similar securities in the market after this offering or the perception that such sales or issuances could occur.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This reoffer prospectus and the documents incorporated herein by reference contain forward-looking statements within the meaning of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “could,” “would,” “expect,” “plan,” “intend,” “anticipate,” “believe,” “estimate,” “project,” “predict,” “forecast,” “potential,” “likely” or “possible”, as well as the negative of such expressions, and similar expressions intended to identify forward-looking statements. Any or all of our forward-looking statements in this report and in the documents that we have referred you to may turn out to be wrong. They can be affected by inaccurate assumptions we might make or by known or unknown risks and uncertainties. Therefore, you should not place undue reliance on any such forward-looking statements. The factors that could cause actual results to differ from those expressed or implied by our forward-looking statements include, among others:

general economic conditions in the markets where we operate;

increased industry competition and downward pressures on bid/offer spreads and electronic brokerage commissions;

risks inherent to the electronic market making and brokerage businesses;

implied versus actual price volatility levels of the products in which we make markets;

the general level of interest rates;

failure to protect or enforce our intellectual property rights in our proprietary technology;

our ability to keep up with rapid technological change;

system failures and disruptions;

non-performance of third-party vendors;

conflicts of interest and other risks due to our ownership and holding company structure;

the loss of key executives and failure to recruit and retain qualified personnel;

the risks associated with the expansion of our business;

our possible inability to integrate any businesses we acquire;

compliance with laws and regulations, including those relating to the securities industry; and

other factors discussed under “Risk Factors” in this reoffer prospectus.

Before you purchase our securities, you should read this reoffer prospectus and the documents that we reference or incorporate by reference in this reoffer prospectus, the prospectus or the registration statement of which this reoffer prospectus is a part completely and with the understanding that our actual future results may be materially different from what we expect. Our business, financial condition, results of operations, and prospects may change. We may not update these forward-looking statements, even though our situation may change in the future, unless we have obligations under the federal securities laws to update and disclose material developments related to previously disclosed information. We qualify all of the information presented or incorporated by reference in this reoffer prospectus, and particularly our forward-looking statements, by these cautionary statements.

USE OF PROCEEDS

We intend to use the net proceeds from the sale of the common stock to recover the withholding taxes paid to tax authorities on behalf of employees who have elected or may hereafter elect to have the Company withhold shares to cover their tax obligations related to the vesting of shares under the Plan.

SELLING STOCKHOLDERS

This reoffer prospectus relates to shares that are being registered for reoffer and resale of up to 6,400,000 shares of our Class A common stock, by the Selling Stockholder who has received or acquired, or may hereafter receive or acquire, the shares pursuant to the Plan. The Selling Stockholder intends to resell the shares of common stock from time to time. The Plan provides employees with two options to pay for their withholding tax obligations which become due when shares vest: either (1) reimburse the Company via cash payment, or (2) elect to have the Selling Stockholder withhold a portion of the vesting shares. In the case of employees who elect to have the Selling Stockholder withhold shares to cover their tax obligations, those shares are transferred to the Selling Stockholder. The Selling Stockholder, in turn, sells those shares in open market transactions, within a certain period of time, to recover the amount paid to the tax authorities on the employees’ behalf. The number of shares covered by this reoffer prospectus represents the Company’s estimate of shares that will be withheld from employees related to the vesting of Plan shares over the next nine years based on current tax rates and historical employee elections. The following table sets forth (a) the name of the Selling Stockholder; (b) the number of shares of common stock beneficially owned by the Selling Stockholder; (c) the maximum number of shares of common stock that the Selling Stockholder may offer for sale from time to time pursuant to this reoffer prospectus, whether or not the Selling Stockholder has any present intention to do so and whether or not such shares have previously been issued to the Selling Stockholders or may in the future be issued, if at all; and (d) the number of shares of common stock and the percentage of common stock that would be beneficially owned by the Selling Stockholder assuming the sale of all shares offered hereby. All information with respect to beneficial ownership has been furnished by the Selling Stockholder.

Information on the shares offered pursuant to this reoffer prospectus, as listed below, does not necessarily indicate that the Selling Stockholder presently intends to sell any or all of the shares so listed. Because the Selling Stockholder may sell none, some or all of the shares owned by the Selling Stockholder which are included in this reoffer prospectus, no estimate can be given as to the number of shares available for resale hereby that will be held by the Selling Stockholder upon the termination of the offering made hereby. We have therefore assumed, for purposes of the following table, that the Selling Stockholder will sell all of the shares owned by the Selling Stockholder that are being offered hereby, but will not sell any other shares of our common stock that the Selling Stockholder presently owns.

The address of the Selling Stockholder is One Pickwick Plaza, Greenwich, Connecticut 06830.


						SHARES BENEFICIALLY OWNED
	SHARES BENEFICIALLY OWNED			NUMBER OF		UPON COMPLETION
	PRIOR TO THIS OFFERING			SHARES		OF THE OFFERING
				BEING
NAME	NUMBER		PERCENT	OFFERED		NUMBER	PERCENT
IBG LLC, a Subsidiary of the Company	0	1	0%	6,400,000	2	0	0%

(1)	From time to time shares will be transferred by Plan participants to the Selling Stockholder when they make the election to cover their tax obligations by having a portion of their vested shares withheld.

(2)	Represents the Company’s estimate of the amount of shares that will be withheld from employees related to the vesting of Plan shares over the next nine years based on current tax rates and historical employee elections.

PLAN OF DISTRIBUTION

We may sell the securities offered pursuant to this prospectus in any of the following ways:

directly to one or more purchasers;

through agents;

through underwriters, brokers or dealers; or

through a combination of any of these methods of sale.

We will pay all fees and expenses incident to the registration of the shares of Class A common stock. Interactive Brokers LLC, a subsidiary of the Selling Stockholder, will act as the broker-dealer in selling the securities, although other broker-dealers may be used.

The anti-manipulation rules of Regulation M under the Exchange Act may apply to sales of our Class A common stock by the Selling Stockholder.

DESCRIPTION OF CAPITAL STOCK

The following is a summary of our capital stock and provisions of our certificate of incorporation and bylaws, as each is currently in effect. This summary does not purport to be complete and is qualified in its entirety by the provisions of our certificate of incorporation and bylaws, copies of which are incorporated by reference as exhibits to this registration statement.

Our authorized capital stock consists of 1,000,000,000 shares of Class A common stock, par value $0.01 per share, 100 shares of Class B common stock, par value $0.01 per share and 10,000 shares of preferred stock. In this section, when we refer to “common stock,” we are referring to Class A common stock and Class B common stock, taken as a whole.

Common Stock

Class A Common Stock

Voting rights

The holders of Class A common stock are entitled to one vote per share. Holders of shares of Class A common stock are not entitled to cumulate their votes in the election of directors. Generally, all matters to be voted on by stockholders must be approved by a majority (or, in the case of election of directors, by a plurality) of the votes entitled to be cast by all shares of Class A common stock and Class B common stock present in person or represented by proxy, voting together as a single class. Except as otherwise provided by law, amendments to our amended and restated certificate of incorporation must be approved by a majority of the combined voting power of all shares of Class A common stock and Class B common stock, voting together as a single class. However, amendments to the amended and restated certificate of incorporation that would alter or change the powers, preferences or special rights of the Class A common stock so as to affect them adversely also must be approved by a majority of the votes entitled to be cast by the holders of the shares affected by the amendment, voting as a separate class. Notwithstanding the foregoing, any amendment to our amended and restated certificate of incorporation to increase or decrease the authorized shares of any class of common stock shall be approved upon the affirmative vote of the holders of a majority of the shares of Class A common stock and Class B common stock, voting together as a single class.

Dividend rights

Holders of Class A common stock share ratably (based on the number of shares of common stock held) in any dividend declared by our board of directors. Dividends consisting of shares of Class A common stock may be paid only as follows: (i) shares of Class A common stock may be paid only to holders of shares of Class A common stock; and (ii) shares are paid proportionally with respect to each outstanding share of Class A common stock. We may not subdivide or combine shares of either class of common stock without at the same time proportionally subdividing or combining shares of the other class. Dividends payable to holders of Class B common stock can only be paid if dividends in the same amount per share are simultaneously paid to holders of Class A common stock.

Liquidation rights

On our liquidation, dissolution or winding up, all holders of Class A common stock are entitled to share ratably in any assets available for distribution to holders of shares of common stock.

Other matters

In accordance with our amended and restated certificate of incorporation and the amended and restated limited liability company agreement pursuant to which IBG LLC is governed, the net cash proceeds received by us from any future issuance of shares of common stock will either be used to purchase IBG LLC membership interests from Holdings or be transferred to IBG LLC in exchange for newly issued membership interests equal in number to such number of shares of common stock issued by us. The number of outstanding IBG LLC membership interests owned by us, therefore, equals the number of outstanding shares of our common stock, adjusted for any shares held in treasury stock. As a result, existing common stockholders experience no material dilution with regard to their equity interest in IBG LLC as a result of the issuance of additional shares of our common stock.

In the event of our merger or consolidation with or into another company in connection with which shares of either class of common stock are converted into or exchangeable for shares of stock, other securities or property (including cash), all holders of common stock, regardless of class, are entitled to receive the same kind and amount of shares of stock and other securities and property (including cash), provided that if shares of either class of common stock are exchanged for shares of capital stock, such shares exchanged for or changed into may differ to the extent that the Class A common stock and the Class B common stock differ.

No shares of either class of common stock are subject to redemption or have preemptive rights to purchase additional shares of either class of common stock. All outstanding shares of Class A common stock have been legally issued, fully paid and nonassessable.

Class B Common Stock

Voting rights

The holders of Class B common stock, in the aggregate, are entitled to the number of votes equal to the number of IBG LLC membership interests held by such holders. IBG Holdings LLC, as the sole holder of the Class B common stock, is entitled to approximately 343.3 million votes, as of September 30, 2015.

Holders of shares of Class B common stock are not entitled to cumulate their votes in the election of directors. Generally, all matters to be voted on by stockholders must be approved by a majority (or, in the case of election of directors, by a plurality) of the votes entitled to be cast by all shares of Class B common stock and Class A common stock present in person or represented by proxy, voting together as a single class. Except as otherwise provided by law, amendments to the amended and restated certificate of incorporation must be approved by a majority of the combined voting power of all shares of Class B common stock and Class A common stock, voting together as a single class. However, amendments to the certificate of incorporation that would alter or change the powers, preferences or special rights of the Class B common stock so as to affect them adversely also must be approved by a majority of the votes entitled to be cast by the holders of the shares affected by the amendment, voting as a separate class. Notwithstanding the foregoing, any amendment to our amended and restated certificate of incorporation to increase or decrease the authorized shares of any class of common stock shall be approved upon the affirmative vote of the holders of a majority of the shares of Class B common stock and Class A common stock, voting together as a single class.

Dividend rights

Holders of Class B common stock share ratably (based on the number of shares of common stock held) in any dividend declared by the board of directors. Dividends consisting of shares of Class B common stock may be paid only as follows: (i) shares of Class B common stock may be paid only to holders of shares of Class B common stock; and (ii) shares are paid proportionally with respect to each outstanding share of Class B common stock. We may not subdivide or combine shares of either class of common stock without at the same time proportionally subdividing or combining shares of the other class. Dividends payable to holders of Class B common stock can only be paid if dividends in the same amount per share are simultaneously paid to holders of Class A common stock.

Liquidation rights

On our liquidation, dissolution or winding up, all holders of Class B common stock are entitled to share ratably in any assets available for distribution to holders of shares of common stock.

Other matters

In the event of our merger or consolidation with or into another company in connection with which shares of either class of common stock are converted into or exchangeable for shares of stock, other securities or property (including cash), all holders of common stock, regardless of class, are entitled to receive the same kind and amount of shares of stock and other securities and property (including cash), provided that, if shares of either class of common stock are exchanged for shares of capital stock, such shares exchanged for or changed into may differ to the extent that the Class A common stock and the Class B common stock differ.

No shares of either class of common stock are subject to redemption or will have preemptive rights to purchase additional shares of either class of common stock. All outstanding shares of Class B common stock have been legally issued and are fully paid and nonassessable.

Preferred Stock

Our board of directors has the authority, without further action by our stockholders, to issue our preferred stock in one or more series and to fix the rights, preferences, privileges, and restrictions thereof. These rights, preferences, and privileges include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms, and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of our common stock. The issuance of our preferred stock could adversely affect the voting power of our holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of our preferred stock could have the effect of delaying, deferring, or preventing a change in our control.

IBG LLC Membership Interests and Amended and Restated Limited Liability Company Agreement of IBG LLC

Our primary asset is our ownership of approximately 15.7% of the IBG LLC membership interests, and our controlling interest and related contractual rights as the sole managing member of IBG LLC, as of September 30, 2015. There are approximately 407.0 million IBG LLC membership interests issued and outstanding, approximately 63.7 million, or 15.7%, of which are owned by us, and approximately 343.3 million, or 84.3%, of which are owned by Holdings as of September 30, 2015. All IBG LLC membership interests are identical and have the same voting and other rights.

Our only business is to act as the sole managing member of IBG LLC, and, as such, we operate and control all of the business and affairs of IBG LLC, have all of the rights and powers which may be possessed by managing members under the Connecticut Limited Liability Company Act and are able to consolidate IBG LLC’s financial results into our financial statements. Except with the prior written consent of both members of IBG LLC, we do not have the authority to:

conduct any act in contravention of IBG LLC’s amended and restated limited liability company agreement;

knowingly perform any act that would subject any member to personal liability for debts or obligations of IBG LLC in any jurisdiction;

engage in any activity which substantially changes the nature of IBG LLC’s business;

sell all or a substantial portion of the property of IBG LLC;

merge or consolidate IBG LLC with or into another entity;

convert IBG LLC, by whatever means, into a corporation or another form of business entity; or

dissolve or liquidate IBG LLC.

The amended and restated limited liability company agreement of IBG LLC provides that the number of IBG LLC membership interests will equal the sum of the number of shares of common stock outstanding and the number of outstanding membership interests of Holdings. From time to time and without regard to the exchange agreement among us, IBG LLC, Holdings and the historical members of IBG LLC, we may issue additional shares of common stock under incentive plans for employees (including the Plan), in exchange for capital or in other arrangements that benefit IBG LLC. In any such case, it is the intention of the members that a corresponding number of IBG LLC membership interests shall be issued to us in exchange for the consideration received by us for our issuance of additional shares of common stock. If any shares of common stock are issued subject to restrictions resulting in forfeiture to us or are otherwise redeemed by us, a corresponding number of IBG LLC membership interests shall be surrendered to IBG LLC by us for cancellation. Similarly, if any common shares of Holdings are forfeited to Holdings and as a result thereof are no longer outstanding, a corresponding number of IBG LLC membership interests shall be surrendered to IBG LLC by Holdings for cancellation. These and other adjustments to the number of IBG LLC membership interests outstanding may be made from time to time as necessary to properly reflect the relative interests of the members.

In accordance with the amended and restated limited liability company agreement pursuant to which IBG LLC is governed, net profits, net losses and distributions of IBG LLC are allocated and made to its members pro rata in accordance with the respective percentages of their membership interests in IBG LLC. Accordingly, net profits and net losses of IBG LLC are allocated, and distributions by IBG LLC are made, approximately 15.7% to us and approximately 84.3% to Holdings as of September 30, 2015.

Pursuant to the terms of the amended and restated limited liability company agreement of IBG LLC, we, as the managing member of IBG LLC, can cause IBG LLC to make distributions to its members, including us, to the extent necessary to enable such members to pay taxes incurred with respect to their allocable shares of taxable income of IBG LLC, using a tax rate no less than the actual combined federal, state and local income tax rates applicable to our allocable share of taxable income. Any distributions by IBG LLC in excess of such tax distributions will be at the discretion of our board of directors and will depend on IBG LLC’s strategic plans, financial results and condition, contractual, legal, financial and regulatory restrictions on distributions, capital requirements, business prospects and such other factors as our board of directors, in exercising our authority as managing member of IBG LLC, considers to be relevant to such determination.

Section 203 of the General Corporation Law of the State of Delaware

We are subject to Section 203 of the General Corporation Law of the State of Delaware, which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years following the date that such stockholder became an interested stockholder, with the following exceptions:

prior to such date, the board of directors of the corporation approved either the business combination or the transaction that resulted in the stockholder becoming an interested holder;

upon consummation of the transaction that resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the number of shares outstanding those shares owned by persons who are directors and also officers and by employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; and

on or subsequent to such date, the business combination is approved by the board of directors and authorized at an annual or special meeting of the stockholders, and not by written consent, by the affirmative vote of at least 662/3% of the outstanding voting stock that is not owned by the interested stockholder.

Section 203 defines business combination to include the following:

any merger or consolidation involving the corporation and the interested stockholder;

any sale, transfer, pledge or other disposition of 10% or more of the assets of the corporation involving the interested stockholder;

subject to certain exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation to the interested stockholder;

any transaction involving the corporation that has the effect of increasing the proportionate share of the stock or any class or series of the corporation beneficially owned by the interested stockholder; or

the receipt by the interested stockholder of the benefit of any loss, advances, guarantees, pledges, or other financial benefits by or through the corporation.

In general, Section 203 defines an interested stockholder as an entity or person beneficially owning 15% or more of the outstanding voting stock of the corporation or any entity or person affiliated with or controlling or controlled by such entity or person.

Transfer Agent and Registrar

The transfer agent and registrar for shares of our common stock is Computershare Shareholder Services, Inc.

Listing

Our common stock is listed on The Nasdaq Global Select Market under the symbol “IBKR.”

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy any document we file with the SEC at the public reference room maintained by the SEC at 100 F Street, N.E., Washington, D.C. 20549. Copies also may be obtained from the Public Reference Section of the SEC at 100 F Street, N.E., Washington, D.C. 20549 at prescribed rates. You may obtain information on the operation of the public reference room by calling the SEC at 1-800-SEC-0330. In addition, the SEC maintains an Internet site (http://www.sec.gov) that contains reports, proxy and information statements and other information regarding registrants who file electronically with the SEC.

This reoffer prospectus is part of a registration statement that we filed with the SEC. The registration statement contains more information than this reoffer prospectus regarding us and our securities, including certain exhibits and schedules. You can obtain a copy of the registration statement from the SEC at the address listed above or from the SEC’s Internet site (http://www.sec.gov).

INFORMATION INCORPORATED BY REFERENCE

The SEC allows us to “incorporate by reference” information that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this reoffer prospectus, and information that we file later with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings we will make with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, or the Exchange Act, after the date of this reoffer prospectus but before the termination of any offering made under this reoffer prospectus:

our annual report on Form 10-K for the fiscal year ended December 31, 2014 (filed with the SEC on March 2, 2015);

our quarterly reports on Form 10-Q for the quarter ended March 31, 2015 and June 30, 2015 (filed with the SEC on May 11, 2015 and August 10, 2015, respectively);

our definitive proxy statement filed with the SEC on March 13, 2015 and additional solicitation materials also filed with the SEC on March 13, 2015;

our current reports on Form 8-K, filed with the SEC on January 20, 2015, April 21, 2015, April 29, 2015, July 21 2015 and July 24, 2015; and

the description of our common stock contained in the registration statement on Form 8-A, filed with the SEC on May 2, 2007.

Upon oral or written request and at no cost to the requester, we will provide to any person, including a beneficial owner, to whom a reoffer prospectus is delivered, a copy of any or all the information that has been incorporated by reference in this reoffer prospectus but not delivered with this reoffer prospectus. All requests should be made to: Interactive Brokers Group, Inc., One Pickwick Plaza, Greenwich, Connecticut 06830, Attn: Corporate Secretary. You should rely only on the information incorporated by reference or provided in this reoffer prospectus. We have not authorized anyone to provide you with different information. You should not assume that the information in this reoffer prospectus or the documents incorporated by reference is accurate as of any date other than the date on the front of this reoffer prospectus or those documents.

LEGAL MATTERS

The validity of the securities reoffered hereby will be passed upon for us by Dechert LLP, New York, New York.

EXPERTS

The consolidated financial statements, and the related financial statement schedule, incorporated in this Prospectus by reference from the Company’s Annual Report on Form 10-K for the year ended December 31, 2014, and the effectiveness of the Company’s internal control over financial reporting have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their reports, which are incorporated herein by reference. Such consolidated financial statements and financial statement schedule have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

Common Stock

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 3. Incorporation of Documents by Reference

our annual report on Form 10-K for the fiscal year ended December 31, 2014 (filed with the SEC on March 2, 2015);

our quarterly reports on Form 10-Q for the quarter ended March 31, 2015 and June 30, 2015 (filed with the SEC on May 11, 2015 and August 10, 2015, respectively);

our definitive proxy statement filed with the SEC on March 13, 2015 and additional solicitation materials also filed with the SEC on March 13, 2015;

our current reports on Form 8-K, filed with the SEC on January 20, 2015, April 21, 2015, April 29, 2015, July 21 2015 and July 24, 2015; and

the description of our common stock contained in the registration statement on Form 8-A, filed with the SEC on May 2, 2007.

Item 4. Description of Securities.

Not Applicable

Item 5. Interest of Named Experts and Counsel

Earl H. Nemser, the Company’s vice chairman and one of its directors, is also Special Counsel to the law firm of Dechert LLP, which has rendered legal services to the Company and its subsidiaries, including IBG LLC, since 2005.

Item 6. Indemnification of Directors and Officers.

Section 145 of the Delaware General Corporation Law (the “DGCL”) provides that a corporation may indemnify directors and officers as well as other employees and individuals against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with any threatened, pending or completed actions, suits or proceedings in which such person is made a party by reason of such person being or having been a director, officer, employee of or agent to the company. The statute provides that it is not exclusive of other rights to which those seeking indemnification may be entitled under any by-law, agreement, vote of stockholders or disinterested directors or otherwise.

As permitted by the DGCL, our certificate of incorporation includes a provision that eliminates the personal liability of our directors for monetary damages for breach of fiduciary duty as a director, except for liability (1) for any breach of the director’s duty of loyalty to us or our stockholders; (2) for acts or omissions not in good faith or that involve intentional misconduct or a knowing violation of the law; (3) under Section 174 of the DGCL regarding unlawful dividends and stock purchases; or (4) arising as a result of any transaction from which the director derived an improper personal benefit.

As permitted by the DGCL, our bylaws provide that (1) we are required to indemnify our directors and officers to the fullest extent permitted by applicable law; (2) we are permitted to indemnify our other employees to the extent permitted by applicable statutory law; (3) we are required to advance expenses to our directors and officers in connection with any legal proceeding, subject to the provisions of applicable statutory law; and (4) the rights conferred in our bylaws are not exclusive.

In addition, Delaware law provides that a corporation may advance to a director or officer expenses incurred in defending any action upon receipt of an undertaking by or on behalf of the director or officer to repay the amount advanced if it is ultimately determined that he or she is not entitled to indemnification.

The Company’s directors and officers are also indemnified by IBG LLC pursuant to the Indemnification Agreement dated June 14, 2007 and by Mr. Thomas Peterffy pursuant to the Indemnification Agreement dated October 8, 2014 and subsequently renewed. The Company maintains directors’ and officers’ liability insurance covering certain liabilities incurred by the directors and officers of the Company in connection with the performance of their duties.

Item 7. Exemption for Registration Claimed.

Not Applicable.

Item 8. Exhibits

Exhibit No.		Description
4.1		Amended Interactive Brokers Group, Inc. 2007 Stock Incentive Plan. Filed as Exhibit 10.5 to the Company’s Annual Report on Form 10-K for the Annual Period Ended December 31, 2014 filed by the Company on March 2, 2015.
5.1		Opinions of Dechert LLP Filed as Exhibit 5.1 to each of the Company’s Registration Statements on Form S-8, File Nos. 333-142686, 333-174913 and 333-203358, on May 7, 2007, June 15, 2011 and April 10, 2015, respectively, and incorporated herein by reference.
23.1	*	Consent of Deloitte & Touche LLP
23.2		Consents of Dechert LLP (included in Exhibit 5.1)
23.3		Power of Attorney. Filed as Exhibit 24.1 to each of the Company’s Registration Statements on Form S-8, File Nos. 333-142686, 333-174913 and 333-203358, on May 7, 2007, June 15, 2011 and April 10, 2015, respectively, and incorporated herein by reference.

* Filed herewith

Item 9. Undertakings

(a) The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (a)(1)(i), (a)(1)(ii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in periodic reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed a new registration statement relating to the securities to be offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of this offering.

(4) That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(A) Each prospectus filed by the registrant pursuant to Rule 424(b)(3)shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(B) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

(5) That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

(b) The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act of 1933 and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Greenwich, State of Connecticut, on October 13, 2015.

INTERACTIVE BROKERS GROUP, INC.

By:	/s/ PAUL J. BRODY
	Name:	Paul J. Brody
	Title:	Chief Financial Officer, Treasurer and Secretary

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacity and on the dates indicated.

Signature	Title	Date

/s/ THOMAS PETERFFY	Chairman of the Board of Directors,	October 13, 2015
Thomas Peterffy	Chief Executive Officer (Principal Executive Officer)

/s/ PAUL J. BRODY	Chief Financial Officer, Treasurer,	October 13, 2015
Paul J. Brody	Secretary and Director (Principal Financial Officer)

/s/ DENIS MENDONCA	Controller	October 13, 2015
Denis Mendonca

/s/ *	Director	October 13, 2015
Lawrence E. Harris

/s/ *	Director	October 13, 2015
Hans R. Stoll

/s/ *	Director	October 13, 2015
Richard Gates

*	/s/ Paul J. Brody
	by: Paul J. Brody, as attorney-in-fact.

EXHIBIT INDEX

Exhibit No.		Description
4.1		Amended Interactive Brokers Group, Inc. 2007 Stock Incentive Plan. Filed as Exhibit 10.5 to the Company’s Annual Report on Form 10-K for the Annual Period Ended December 31, 2014 filed by the Company on March 2, 2015.
5.1		Opinions of Dechert LLP. Filed as Exhibit 5.1 to each of the Company’s Registration Statements on Form S-8, File Nos. 333-142686, 333-174913 and 333-203358, on May 7, 2007, June 15, 2011 and April 10, 2015, respectively, and incorporated herein by reference.
23.1	*	Consent of Deloitte & Touche LLP
23.2		Consents of Dechert LLP (included in Exhibit 5.1)
24.1		Power of Attorney. Filed as Exhibit 24.1 to each of the Company’s Registration Statements on Form S-8, File Nos. 333-142686, 333-174913 and 333-203358, on May 7, 2007, June 15, 2011 and April 10, 2015, respectively, and incorporated herein by reference.

* Filed herewith