<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): January 31, 2006

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

        DELAWARE               001-16507                    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

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>


                      INFORMATION TO BE INCLUDED IN REPORT

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

                                    On January 4, 2006, AT&T Corp. (the
                           "Underlying Securities Issuer") filed a Form 15 with
                           the U.S. Securities and Exchange Commission with
                           respect to its common stock and five series of its
                           notes, including the 6.5% notes due 2029 which
                           represent all of the underlying securities (the
                           "Underlying Securities") of PreferredPLUS Trust
                           Certificates Series ATT-1 (the "Trust Certificates").
                           As a result, the Underlying Securities Issuer ceased
                           to be required to file periodic reports under the
                           U.S. Securities Exchange Act of 1934, as amended (the
                           "Termination Event").

                                    On January 23, 2006, a Notice of Termination
                           (as updated on January 6, 2006) was given pursuant to
                           which the Trustee gave notice to the holders of the
                           Trust Certificates and the holders of call warrants
                           relating to the Trust Certificates that the
                           PreferredPLUS Trust Series ATT-1 (the "Trust") would
                           distribute the Underlying Securities on a pro rata
                           basis and terminate the Trust on February 2, 2006
                           unless the holders of the call warrants elected to
                           exercise their right to call the Trust Certificates
                           prior to such date.

                                    On January 24, 2006, all of the outstanding
                           call warrants relating to the Trust Certificates were
                           exercised at an exercise price (the "Exercise Price")
                           of US$26.40 per Trust Certificate plus accrued and
                           unpaid distributions to January 31, 2006 (the
                           "Exercise Date"). On January 31, 2006 the Exercise
                           Price was distributed to the holders of Trust
                           Certificates called pursuant to the exercise of the
                           call warrants.

<PAGE>

                                    In addition, following the distribution of
                           the Exercise Price and the consummation of the
                           exercise of the call warrants, the Underlying
                           Securities were distributed on January 31, 2006 to
                           the holders of the Trust Certificates pursuant to
                           Section 3.04(i) of the Standard Terms for Trust
                           Agreements, dated as of February 20, 1998 between
                           Merrill Lynch Depositor, Inc. (the "Depositor") and
                           The Bank of New York, as successor Trustee (the
                           "Trustee"), and Section 13 of the Series Supplement
                           (the "Series Supplement") dated as of May 23, 2001
                           between the Depositor and the Trustee, and in
                           accordance with the definition of Distribution
                           Election under the Series Supplement.

                                    For information with respect to the
                           underlying securities held by PreferredPLUS Trust
                           Series ATT-1, please refer to AT&T Corp.'s
                           (Commission file number 001-01105 ) 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
                           issuer has filed electronically with the SEC.

<PAGE>

                                    Although we have no reason to believe the
                           information concerning the underlying securities or
                           the underlying securities issuer contained in the
                           underlying securities issuer'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 (including, without limitation, no
                           investigation as to its financial condition or
                           creditworthiness) or of the underlying securities has
                           been made. You should obtain and evaluate the same
                           information concerning the underlying securities
                           issuer as you would obtain and evaluate if you were
                           investing directly in the underlying securities or in
                           other securities issued by the underlying securities
                           issuer. There can be no assurance that events
                           affecting the underlying securities or the underlying
                           securities issuer 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.

              Not Applicable.

        (b)   Pro forma financial information.

              Not Applicable.

        (c)   Shell company transactions.

              Not applicable

        (d)   Exhibits.

              99.1  Trustee's report in respect of the January 31, 2006
                    distribution to holders of the PreferredPLUS Trust
                    Certificates Series ATT-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 14, 2006               By: /s/ Stephan Kuppenheimer
                                          ------------------------------
                                      Name:  Stephan Kuppenheimer
                                      Title: President





<PAGE>


                                  EXHIBIT INDEX


99.1 Trustee's report in respect of the January 31, 2006 distribution to holders
     of the PreferredPLUS Trust Certificates Series ATT-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): January 31, 2006

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

        DELAWARE               001-16507                    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

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))
INFORMATION TO BE INCLUDED IN REPORT

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

                                    On January 4, 2006, AT&T Corp. (the
                           "Underlying Securities Issuer") filed a Form 15 with
                           the U.S. Securities and Exchange Commission with
                           respect to its common stock and five series of its
                           notes, including the 6.5% notes due 2029 which
                           represent all of the underlying securities (the
                           "Underlying Securities") of PreferredPLUS Trust
                           Certificates Series ATT-1 (the "Trust Certificates").
                           As a result, the Underlying Securities Issuer ceased
                           to be required to file periodic reports under the
                           U.S. Securities Exchange Act of 1934, as amended (the
                           "Termination Event").

                                    On January 23, 2006, a Notice of Termination
                           (as updated on January 6, 2006) was given pursuant to
                           which the Trustee gave notice to the holders of the
                           Trust Certificates and the holders of call warrants
                           relating to the Trust Certificates that the
                           PreferredPLUS Trust Series ATT-1 (the "Trust") would
                           distribute the Underlying Securities on a pro rata
                           basis and terminate the Trust on February 2, 2006
                           unless the holders of the call warrants elected to
                           exercise their right to call the Trust Certificates
                           prior to such date.

                                    On January 24, 2006, all of the outstanding
                           call warrants relating to the Trust Certificates were
                           exercised at an exercise price (the "Exercise Price")
                           of US$26.40 per Trust Certificate plus accrued and
                           unpaid distributions to January 31, 2006 (the
                           "Exercise Date"). On January 31, 2006 the Exercise
                           Price was distributed to the holders of Trust
                           Certificates called pursuant to the exercise of the
                           call warrants.
In addition, following the distribution of
                           the Exercise Price and the consummation of the
                           exercise of the call warrants, the Underlying
                           Securities were distributed on January 31, 2006 to
                           the holders of the Trust Certificates pursuant to
                           Section 3.04(i) of the Standard Terms for Trust
                           Agreements, dated as of February 20, 1998 between
                           Merrill Lynch Depositor, Inc. (the "Depositor") and
                           The Bank of New York, as successor Trustee (the
                           "Trustee"), and Section 13 of the Series Supplement
                           (the "Series Supplement") dated as of May 23, 2001
                           between the Depositor and the Trustee, and in
                           accordance with the definition of Distribution
                           Election under the Series Supplement.

                                    For information with respect to the
                           underlying securities held by PreferredPLUS Trust
                           Series ATT-1, please refer to AT&T Corp.'s
                           (Commission file number 001-01105 ) 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
                           issuer has filed electronically with the SEC.
Although we have no reason to believe the
                           information concerning the underlying securities or
                           the underlying securities issuer contained in the
                           underlying securities issuer'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 (including, without limitation, no
                           investigation as to its financial condition or
                           creditworthiness) or of the underlying securities has
                           been made. You should obtain and evaluate the same
                           information concerning the underlying securities
                           issuer as you would obtain and evaluate if you were
                           investing directly in the underlying securities or in
                           other securities issued by the underlying securities
                           issuer. There can be no assurance that events
                           affecting the underlying securities or the underlying
                           securities issuer 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.

              Not Applicable.

        (b)   Pro forma financial information.

              Not Applicable.

        (c)   Shell company transactions.

              Not applicable

        (d)   Exhibits.

              99.1  Trustee's report in respect of the January 31, 2006
                    distribution to holders of the PreferredPLUS Trust
                    Certificates Series ATT-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 14, 2006               By: /s/ Stephan Kuppenheimer
                                          ------------------------------
                                      Name:  Stephan Kuppenheimer
                                      Title: President
EXHIBIT INDEX

99.1 Trustee's report in respect of the January 31, 2006 distribution to holders
     of the PreferredPLUS Trust Certificates Series ATT-1.