Washington, DC 20549

                    Under the Securities Exchange Act of 1934
                                (Amendment No. 0)

                            VERTEX PHARMACEUTICALS, INC.
                                (Name of Issuer)

                         (Title of Class of Securities)

                                  (CUSIP NUMBER)

                                  Rebecca Cinci
                       Pioneer Investment Management, Inc.
                                 60 State Street
                                Boston, MA 02109
              (Name, Address and Telephone Number of Person Authorized to
                          Receive Notices and Communications)

                                 February 29, 2004
             (Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box. [x]

1.        Name of Reporting Pioneer Global Asset Person Management S.p.A.

          IRS Identification                     98-0362802
          No. of Above

2.        Check the Appropriate Box (a) of A Member of Group (See Instructions)

3.        SEC Use Only

4.        Source of Funds (See instructions) 00

5.        Check if Disclosure of Legal Proceedings Is Required Pursuant to Items
          2(d) or 2(e)

6.        Citizenship of Place of
          Organization                           Milan, Italy

          Number of                            7.  Sole Voting       6,128,313
          Shares                                   Power
          Beneficially Owned                   8.  Shared Voting     0
          by Each Reporting                        Power
          Person With                          9.  Sole Dispositive  6,128,313
                                               10. Shared Disposi-   0
                                                   Dispositive Power

11.       Aggregate Amount Beneficially
          Owned by Each
          Reporting Person                      6,128,313

12.       Check if the aggregate Amount in Row (11) Exclude Certain Shares (See
          Instructions) [ ]

13.       Percent of Class Represented By Amount in Row 11.  7.31%

14.       Type of Reporting
          Person (See Instructions)              HC

Item 1.  Security and Issuer
- ----------------------------

         The class of equity securities to which this Statement relates is the
common stock, $0.01 par value per share (the "Common Stock"), of Vertex
Pharmaceuticals, Inc. (the "Issuer"), the executive office of which is located
at 130 Waverly Street, Cambridge, MA 02139-4242

Item 2.  Identity and Background
- --------------------------------

(a)  Name: Pioneer Global Asset Management S.p.A.

(b)  Residence or Business Address: Galleria San Carlo 6, 20122 Milan, Italy

(c)  Present Principal Occupation or Employment: Financial Services, Galleria
     San Carlo 6, 20122 Milan, Italy

(d)  None.

(e)  None.

(f)  Citizenship: Italy

Item 3.  Source and Amount of Funds or Other Consideration
- ----------------------------------------------------------

EURO 5,905,653 and USD 70,515,966 from the capital of the Funds has been used
in making purchases of 6,128,313 shares that convert into Common Stock of
Vertex Pharmaceuticals, Inc.

Item 4.  Purpose of Transaction
- -------------------------------

The Funds acquired ownership of Vertex Pharmaceuticals, Inc. reported herein
for the purposes of investment. The Funds may, in the future, purchase
additional shares of Common Stock of Vertex Pharmaceuticals, Inc. or sell such

The Funds do not have any present plan or proposal which would relate to or
result in transactions of the kind described in paragraphs (a) through (j) of
Item 4 of Schedule 13d-101 of the Securities and Exchange Commission. The Funds
reserve the right, in the future, to adopt such plans or proposals.

     (a)  the acquisition by any person of additional securities of the Issuer,
          or the disposition of securities of the Issuer;

     (b)  an extraordinary corporate transaction, such as a merger,
          reorganization or liquidation, involving the Issuer or any of its

     (c)  a sale or transfer of a material amount of assets of the Issuer or any
          of its subsidiaries;

     (d)  any change in the present board of directors or management of the
          Issuer, including any plans or proposals to change the number or term
          of directors or to fill any existing vacancies on the board;

     (e)  any material change in the present capitalization or dividend policy
          of the Issuer;

     (f)  any other material change in the Issuer's business or corporate

     (g)  changes in the Issuer's articles of incorporation, bylaws or
          instruments corresponding thereto or other actions which may impede
          the acquisition of control of the Issuer by any persons;

     (h)  causing a class of securities of the Issuer to be delisted from a
          national securities exchange or to cease to be authorized to be quoted
          in an inter-dealer quotation system of a registered national
          securities association;

     (i)  a class of equity securities of the Issuer becoming eligible for
          termination of registration pursuant to Section 12(g)(4) of the
          Securities Exchange Act of 1934, as amended; or

     (j)  any action similar to any of those enumerated above.

Item 5.  Interest in Securities of the Issuer
- ---------------------------------------------

         (a) The reporting person beneficially owns 6,128,313 shares of the
Issuer as of the date of this statement, representing 7.31% of the issued and
outstanding shares. This includes $91,557,000 5.75% 02/15/2011 convertible bonds
which represent 6,128,313 shares of common stock upon conversion.

         (b) Pioneer Global Asset Management S.p.A exercises sole voting and
dispositive power over 6,128,313 shares.

         (c) Within the last 60 days of the event date of this filing, the
Funds' ownership of Vertex Pharmaceuticals, Inc. shares that convert into Common
Stock increased to more than 5% of the adjusted outstanding shares of said
class.  The funds have purchased and sold shares on the open market as described
in the table below:

Pioneer US High Yield Corp. Bond Sub Fund Transactions:

               Transaction       Number of
Date              Type             Shares         Price
- ----         - ---------       - -------        - ---
02/17/04        Exchange         6,800,000         N/A

Pioneer High Yield Fund Transactions:

               Transaction       Number of
Date              Type             Shares         Price
- ----         - ---------       - -------        - ---
02/17/04        Exchange         87,857,000       N/A
02/23/04          Sale           700,000          1.02
02/25/04          Sale           600,000          1.02
02/26/04          Sale           1,200,000        1.02
02/27/04          Sale           1,000,000        1.02

Pioneer Global High Yield Fund Transactions:

               Transaction       Number of
Date              Type             Shares         Price
- ----         - ---------       - -------        - ---
02/17/04        Exchange         10,000           N/A
02/18/04          Sale           10,000           1.00

Pioneer High Yield VCT Portfolio Transactions:

               Transaction       Number of
Date              Type             Shares         Price
- ----         - ---------       - -------        - ---
02/17/04        Exchange         400,000          N/A

Pioneer Strategic Income Fund Transactions:

               Transaction       Number of
Date              Type             Shares         Price
- ----         - ---------       - -------        - ---
02/17/04        Exchange         695,000          N/A
02/18/04          Sale           695,000          1.00

Pioneer Strategic Income VCT Portfolio Transactions:

               Transaction       Number of
Date              Type             Shares         Price
- ----         - ---------       - -------        - ---
02/17/04        Exchange         140,000          N/A
02/18/04          Sale           140,000          1.00

         (d) No other person has any interest in the securities reported on
pursuant to his Schedule 13D.

         (e) Not applicable.

Item 6. Contracts, Arrangements, Understanding, or Relationships With Respect to
        Securities of the Issuer
- ------------------------------------------------------------------------------

         There are no contracts, arrangements, understandings, or relationships
between the undersigned and any other person with respect to the issuer's
securities, including but not limited to the transfer or voting of securities,
finder's fees, joint ventures, loan or option arrangements, puts or calls,
guarantees of profits, division of profits or loss, the giving or withholding of
proxies, or otherwise.

Item 7.  Material to be Filed as Exhibits
- -----------------------------------------

         Not applicable.

- -------

         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete, and

          March 12, 2004

          /s/Dario Frigerio
          Dario Frigerio
          Chief Executive Officer