1 As filed with the Securities and Exchange Commission on April 30, 2001 Registration No. 333-33152 ================================================================================ SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-3 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 SIPEX CORPORATION (Exact name of registrant as specified in its charter) MASSACHUSETTS 04-6135748 (State or other jurisdiction of (I.R.S. Employer Identification No.) incorporation or organization) 22 LINNELL CIRCLE, BILLERICA, MA 01821 (Address, including zip code, and telephone number, including area code, of Registrant's principal executive offices) -------------------- JAMES E. DONEGAN CHIEF EXECUTIVE OFFICER SIPEX CORPORATION 22 LINNELL CIRCLE BILLERICA, MASSACHUSETTS 01821 (Name and address of agent for service of process) (978) 667-8700 (Telephone number, including area code, of agent for service) -------------------- Copy to: KENNETH J. GORDON, ESQ. TESTA, HURWITZ & THIBEAULT, LLP 125 HIGH STREET BOSTON, MASSACHUSETTS 02110 (617) 248-7000 2 The Registrant hereby removes from registration under this Registration Statement (No. 333-33152) 1,948,873 shares of Common Stock, $.01 par value per share, registered hereunder (all shares originally registered hereunder being referred to as the "Offered Shares") that have not been sold pursuant to this Registration Statement. The Offered Shares were registered in connection with the Registrant's acquisition of Calogic and its subsidiary, Alpha Semiconductor, Inc. (the "Acquisition"). By the terms of this Registration Statement and a Registration Rights Agreement by and among the Registrant and the former stockholders of Calogic and Alpha Semiconductor, Inc., the Registrant was required to keep this Registration Statement effective until November 23, 2000, the first anniversary of the closing of the Acquisition. As of the date hereof, 1,651,126 Offered Shares have been sold or otherwise transferred by selling stockholders under this Registration Statement. 3 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 of the requirements for filing on Form S-3 and has duly caused this Post-Effective Amendment No. 1 to the registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Billerica, Massachusetts on April 30, 2001. SIPEX Corporation By: /s/ James E. Donegan ------------------------------ James E. Donegan Chief Executive Officer and Chairman of the Board of Directors Pursuant to the requirements of the Securities Exchange Act of 1933, as amended, this Post-Effective Amendment No. 1 to the registration statement has been signed below by the following persons in the capacities indicated on the dates indicated. SIGNATURE TITLE DATE --------- ----- ---- Chief Executive Officer and Chairman of the Board of April 30, 2001 /s/ James E. Donegan Directors (principal executive ------------------------- officer) James E. Donegan Executive Vice President, Chief April 30, 2001 /s/ Frank R. DiPietro Financial Officer and Treasurer ------------------------- (principal financial and Frank R. DiPietro accounting officer) * Director April 30, 2001 ------------------------- Manfred Loeb * Director April 30, 2001 ------------------------- Willy Sansen * Director April 30, 2001 ------------------------- John L. Sprague * Director April 30, 2001 ------------------------- Lionel H. Olmer * Director April 30, 2001 ------------------------- Doug McBurnie /s/ Frank R. DiPietro April 30, 2001 ------------------------- *By: Frank R. DiPietro as Attorney in Fact