As filed with the Securities and Exchange Commission on March 30, 2000 Registration No. 333-78547 Registration No. 333-89169 ================================================================================ SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 FLYCAST COMMUNICATIONS CORPORATION (Exact Name of Registrant as Specified in Its Charter) DELAWARE 77-0431028 (State or Other Jurisdiction of (I.R.S. Employer Incorporation or Organization) Identification Number) 181 FREMONT STREET, SAN FRANCISCO, CALIFORNIA 94105 (Address of Principal Executive Offices) (Zip Code) 1997 STOCK OPTION PLAN 1999 STOCK OPTION PLAN 1999 EMPLOYEE STOCK PURCHASE PLAN 1999 DIRECTORS' STOCK OPTION PLAN (Full Title of the Plans) ANDREW J. HAJDUCKY III VICE PRESIDENT AND TREASURER FLYCAST COMMUNICATIONS CORPORATION 181 FREMONT STREET SAN FRANCISCO, CALIFORNIA 94105 (Name and Address of Agent for Service) (415) 977-1000 (Telephone Number, Including Area Code, of Agent for Service) Copies to: WILLIAM WILLIAMS II, ESQ. VICE PRESIDENT AND GENERAL COUNSEL CMGI, INC. 100 BRICKSTONE SQUARE ANDOVER, MASSACHUSETTS 01810 EXPLANATORY NOTE Pursuant to a Registration Statement on Form S-8 (File No. 333-78547) and a Registration Statement on Form S-8 (File No. 333-89169) (collectively, the "Registration Statements"), Flycast Communications Corporation (the "Registrant") registered shares of its common stock, $.0001 par value per share (the "Registrant Common Stock"), under the Securities Act of 1933, as amended, for offer and issuance pursuant to the Registrant's (i) 1997 Stock Option Plan, (ii) 1999 Stock Option Plan, (iii) 1999 Employee Stock Purchase Plan and (iv) 1999 Directors' Stock Option Plan (collectively, the "Plans"). On January 13, 2000, the Registrant merged with a wholly owned subsidiary of CMGI, Inc. Therefore, this Post-Effective Amendment No. 1 to the Registration Statements is being filed pursuant to the Registrant's undertaking in each such Registration Statement on Form S-8, for the purpose of deregistering all shares of Registrant Common Stock which remain unissued under the Plans. 2 SIGNATURE Pursuant to Rule 478 promulgated under 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-8 and has duly caused this Post- Effective Amendment No. 1 to the Registration Statements to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Andover, The Commonwealth of Massachusetts on March 30, 2000. FLYCAST COMMUNICATIONS CORPORATION By: /s/ Andrew J. Hajducky III -------------------------- Andrew J. Hajducky III Vice President and Treasurer 3