<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D. C. 20549
                           --------------------------

                                    FORM 8-K

                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       The Securities Exchange Act of 1934
                            -------------------------

       Date of Report (Date of earliest event reported): February 15, 2006

                          MERRILL LYNCH DEPOSITOR, INC.
                     (ON BEHALF OF PPLUS TRUST SERIES GSC-1)
             (Exact name of registrant as specified in its charter)

            DELAWARE             001-32153                    13-3891329
        (State or other        (Commission                (I. R. S. Employer
        jurisdiction  of        File Number)              Identification No.)
         incorporation)

     WORLD FINANCIAL CENTER,                                     10080
       NEW YORK, NEW YORK                                     (Zip Code)
      (Address of principal
       executive offices)
                           --------------------------

       Registrant's telephone number, including area code: (212) 449-1000

                      INFORMATION TO BE INCLUDED IN REPORT

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions (see General Instruction A.2.):

[  ]  Written communications pursuant to Rule 425 under the Securities Act (17
      CFR 230.425)

[  ]  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR
      240.14a-12)

[  ]  Pre-commencement communications pursuant to Rule 14d-2(b) under the
      Exchange Act (17 CFR 240.14d-2(b))

[  ]  Pre-commencement communications pursuant to Rule 13e-4(c) under the
      Exchange Act (17 CFR 240.13e-4(c))

<PAGE>

SECTION 1.   REGISTRANT'S BUSINESS AND OPERATIONS

             Not applicable.

SECTION 2.   FINANCIAL INFORMATION

             Not applicable.

SECTION 3.   SECURITIES AND TRADING MARKETS

             Not applicable.

SECTION 4.   MATTERS RELATED TO ACCOUNTANTS AND FINANCIAL STATEMENTS

             Not applicable.

SECTION 5.   CORPORATE GOVERNANCE AND MANAGEMENT

             Not applicable.

SECTION 6.   ASSET-BACKED SECURITIES

             Not applicable.

SECTION 7.   REGULATION FD

             Not applicable.

SECTION 8.   OTHER EVENTS

         ITEM 8.01      OTHER EVENTS

                  99.1  Distribution to holders of the PPLUS Trust Certificates
                        Series GSC-1 on February 15, 2006.

                              For information with respect to the underlying
                        securities held by PPLUS Trust Series GSC-1, please
                        refer to The Goldman Sachs Group, Inc.'s (Commission
                        file number 001-14965) periodic reports, including
                        annual reports on Form 10-K, quarterly reports on Form
                        10-Q and current reports on Form 8-K, and other
                        information on file with the Securities and Exchange
                        Commission (the "SEC"). You can read and copy these
                        reports and other information at the public reference
                        facilities maintained by the SEC at Room 1580, 100 F
                        Street, NE, Washington, D.C. 20549. You may obtain
                        copies of this material for a fee by writing to the
                        SEC's Public Reference Section of the SEC at 100 F
                        Street, NE, Washington, D.C. 20549. You may obtain
                        information about the operation of the Public Reference
                        Room by calling the SEC at 1-800-SEC-0330. You can also
                        access some of this information electronically by means
                        of the SEC's website on the Internet at
                        http://www.sec.gov, which contains reports, proxy and
                        information statements and other information that the
                        underlying securities guarantor and the underlying
                        securities issuer has filed electronically with the SEC.


<PAGE>

                              Although we have no reason to believe the
                        information concerning the underlying securities and the
                        junior subordinated debentures or the underlying
                        securities issuer and the underlying securities
                        guarantor contained in the underlying securities
                        guarantor's Exchange Act reports is not reliable,
                        neither the depositor nor the trustee participated in
                        the preparation of such documents or made any due
                        diligence inquiry with respect to the information
                        provided therein. No investigation with respect to the
                        underlying securities issuer and the underlying
                        securities guarantor (including, without limitation, no
                        investigation as to their financial condition or
                        creditworthiness) or of the underlying securities and
                        the junior subordinated debentures has been made. You
                        should obtain and evaluate the same information
                        concerning the underlying securities issuer and the
                        underlying securities guarantor as you would obtain and
                        evaluate if your investment were directly in the
                        underlying securities or in other securities issued by
                        the underlying securities issuer or the underlying
                        securities guarantor. There can be no assurance that
                        events affecting the underlying securities and the
                        junior subordinated debentures or the underlying
                        securities issuer and the underlying securities
                        guarantor have not occurred or have not yet been
                        publicly disclosed which would affect the accuracy or
                        completeness of the publicly available documents
                        described above.

SECTION 9.   FINANCIAL STATEMENTS AND EXHIBITS

      ITEM 9.01    FINANCIAL STATEMENTS AND EXHIBITS

             (a)   Financial statements of business acquired.

                   None.

             (b)   Pro forma financial information.

                   None.

             (c)   Shell company transactions.

                   Not applicable.

             (d)   Exhibits.

                   99.1    Trustee's report in respect of the February 15,
                           2006distribution to holders of the PPLUS Trust
                           Certificates Series GSC-1.


<PAGE>

                                   SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned, hereunto duly authorized.


                                            MERRILL LYNCH DEPOSITOR, INC.

Date: February 28, 2006                     By:    /s/ Stephan Kuppenheimer
                                                   ---------------------------
                                            Name:  Stephan Kuppenheimer
                                            Title: President

<PAGE>

                                   EXHIBIT INDEX


99.1     Trustee's report in respect of the February 15, 2006 distribution to
         holders of the PPLUS Trust Certificates Series GSC-1.
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SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D. C. 20549
                           --------------------------

                                    FORM 8-K

                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       The Securities Exchange Act of 1934
                            -------------------------

       Date of Report (Date of earliest event reported): February 15, 2006

                          MERRILL LYNCH DEPOSITOR, INC.
                     (ON BEHALF OF PPLUS TRUST SERIES GSC-1)
             (Exact name of registrant as specified in its charter)

            DELAWARE             001-32153                    13-3891329
        (State or other        (Commission                (I. R. S. Employer
        jurisdiction  of        File Number)              Identification No.)
         incorporation)

     WORLD FINANCIAL CENTER,                                     10080
       NEW YORK, NEW YORK                                     (Zip Code)
      (Address of principal
       executive offices)
                           --------------------------

       Registrant's telephone number, including area code: (212) 449-1000

                      INFORMATION TO BE INCLUDED IN REPORT

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions (see General Instruction A.2.):

[  ]  Written communications pursuant to Rule 425 under the Securities Act (17
      CFR 230.425)

[  ]  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR
      240.14a-12)

[  ]  Pre-commencement communications pursuant to Rule 14d-2(b) under the
      Exchange Act (17 CFR 240.14d-2(b))

[  ]  Pre-commencement communications pursuant to Rule 13e-4(c) under the
      Exchange Act (17 CFR 240.13e-4(c))
SECTION 1.   REGISTRANT'S BUSINESS AND OPERATIONS

             Not applicable.

SECTION 2.   FINANCIAL INFORMATION

             Not applicable.

SECTION 3.   SECURITIES AND TRADING MARKETS

             Not applicable.

SECTION 4.   MATTERS RELATED TO ACCOUNTANTS AND FINANCIAL STATEMENTS

             Not applicable.

SECTION 5.   CORPORATE GOVERNANCE AND MANAGEMENT

             Not applicable.

SECTION 6.   ASSET-BACKED SECURITIES

             Not applicable.

SECTION 7.   REGULATION FD

             Not applicable.

SECTION 8.   OTHER EVENTS

         ITEM 8.01      OTHER EVENTS

                  99.1  Distribution to holders of the PPLUS Trust Certificates
                        Series GSC-1 on February 15, 2006.

                              For information with respect to the underlying
                        securities held by PPLUS Trust Series GSC-1, please
                        refer to The Goldman Sachs Group, Inc.'s (Commission
                        file number 001-14965) periodic reports, including
                        annual reports on Form 10-K, quarterly reports on Form
                        10-Q and current reports on Form 8-K, and other
                        information on file with the Securities and Exchange
                        Commission (the "SEC"). You can read and copy these
                        reports and other information at the public reference
                        facilities maintained by the SEC at Room 1580, 100 F
                        Street, NE, Washington, D.C. 20549. You may obtain
                        copies of this material for a fee by writing to the
                        SEC's Public Reference Section of the SEC at 100 F
                        Street, NE, Washington, D.C. 20549. You may obtain
                        information about the operation of the Public Reference
                        Room by calling the SEC at 1-800-SEC-0330. You can also
                        access some of this information electronically by means
                        of the SEC's website on the Internet at
                        http://www.sec.gov, which contains reports, proxy and
                        information statements and other information that the
                        underlying securities guarantor and the underlying
                        securities issuer has filed electronically with the SEC.
Although we have no reason to believe the
                        information concerning the underlying securities and the
                        junior subordinated debentures or the underlying
                        securities issuer and the underlying securities
                        guarantor contained in the underlying securities
                        guarantor's Exchange Act reports is not reliable,
                        neither the depositor nor the trustee participated in
                        the preparation of such documents or made any due
                        diligence inquiry with respect to the information
                        provided therein. No investigation with respect to the
                        underlying securities issuer and the underlying
                        securities guarantor (including, without limitation, no
                        investigation as to their financial condition or
                        creditworthiness) or of the underlying securities and
                        the junior subordinated debentures has been made. You
                        should obtain and evaluate the same information
                        concerning the underlying securities issuer and the
                        underlying securities guarantor as you would obtain and
                        evaluate if your investment were directly in the
                        underlying securities or in other securities issued by
                        the underlying securities issuer or the underlying
                        securities guarantor. There can be no assurance that
                        events affecting the underlying securities and the
                        junior subordinated debentures or the underlying
                        securities issuer and the underlying securities
                        guarantor have not occurred or have not yet been
                        publicly disclosed which would affect the accuracy or
                        completeness of the publicly available documents
                        described above.

SECTION 9.   FINANCIAL STATEMENTS AND EXHIBITS

      ITEM 9.01    FINANCIAL STATEMENTS AND EXHIBITS

             (a)   Financial statements of business acquired.

                   None.

             (b)   Pro forma financial information.

                   None.

             (c)   Shell company transactions.

                   Not applicable.

             (d)   Exhibits.

                   99.1    Trustee's report in respect of the February 15,
                           2006distribution to holders of the PPLUS Trust
                           Certificates Series GSC-1.
SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned, hereunto duly authorized.

                                            MERRILL LYNCH DEPOSITOR, INC.

Date: February 28, 2006                     By:    /s/ Stephan Kuppenheimer
                                                   ---------------------------
                                            Name:  Stephan Kuppenheimer
                                            Title: President
EXHIBIT INDEX

99.1     Trustee's report in respect of the February 15, 2006 distribution to
         holders of the PPLUS Trust Certificates Series GSC-1.