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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                              --------------------

                                    FORM 10-K

                                  ANNUAL REPORT

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

                              --------------------

         For the fiscal year ended:                 Commission file number:
           December 31, 2004                                001-16835

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

             DELAWARE                                 13-3891329
          (State or other                         (I. R. S. Employer
          jurisdiction of                         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

Securities registered pursuant to Section 12(b) of the Act:

PreferredPLUS Trust Certificates Series ALL-1, listed on The New York Stock
Exchange.

Securities registered pursuant to Section 12(g) of the Act:

Not Applicable.

Indicate by check mark whether the Registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the Registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days.

                                 Yes [X] No [ ]

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K is not contained herein, and will not be contained, to the
best of registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this form 10-K or any amendment to this
form 10-K.



Indicate by check mark whether the registrant is an accelerated filer (as
defined in Rule 12b-2 of the Act).

                                 Yes [ ] No [X]

State the aggregate market value of the voting and non-voting common equity held
by non-affiliates of the registrant. The aggregate market value shall be
computed by reference to the price at which the common equity was sold, or the
average bid and asked prices of such common equity, as of the last business day
of the registrant's most recently completed second fiscal quarter.

Not Applicable.

Indicate the number of shares outstanding for each of the registrant's class of
common stock, as of the latest practicable date.

Not Applicable.
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                       DOCUMENTS INCORPORATED BY REFERENCE

None.


         PART I

         ITEM 1.           BUSINESS

                           For information with respect to the underlying
                           securities held by PreferredPLUS Trust Series ALL-1,
                           please refer to Allmerica Financial Corporation's
                           (Commission file number 001-13754) 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 1024, 450 Fifth Street, NW, 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 450 Fifth Street, NW, 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 and underlying securities guarantor have filed
                           electronically with the SEC.

                           Although we have no reason to believe the information
                           concerning the underlying guarantee, the junior
                           subordinated debentures and the underlying securities
                           or the underlying securities guarantor and the
                           underlying securities issuer 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 guarantor and underlying securities issuer
                           (including, without limitation, no investigation as
                           to their respective financial condition or
                           creditworthiness) or of the underlying securities,
                           the junior subordinated debentures or the underlying
                           guarantee 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, junior
                           subordinated debentures and the underlying guarantee
                           or the underlying securities issuer and 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.

         ITEM 2.           PROPERTIES

                           None.

         ITEM 3.           LEGAL PROCEEDINGS

                           None.

         ITEM 4.           SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

                           None.

                                       2
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         PART II

         ITEM 5.           MARKET FOR REGISTRANT'S COMMON EQUITY, RELATED
                           STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY
                           SECURITIES

                           The Trust Certificates issued by PreferredPLUS Trust
                           Series ALL-1 are represented by one or more physical
                           certificates registered in the name of Cede & Co.,
                           the nominee of the Depository Trust Company. The
                           Trust Certificates are listed on the New York Stock
                           Exchange.

         ITEM 6.           SELECTED FINANCIAL DATA

                           Not Applicable.

         ITEM 7.           MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                           CONDITION AND RESULTS OF OPERATIONS

                           Not Applicable.

         ITEM 7A.          QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET
                           RISK

                           Not Applicable.

         ITEM 8.           FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

                           Not Applicable.

         ITEM 9.           CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON
                           ACCOUNTING AND FINANCIAL DISCLOSURE

                           None.

         ITEM 9A.          CONTROLS AND PROCEDURES

                           The Registrant has procedures so as to provide
                           reasonable assurance that its future Exchange Act
                           filings will be filed within the applicable time
                           periods.

         ITEM 9B.          OTHER INFORMATION

                           None.

                                       3
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         PART III

         ITEM 10.          DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

                           Not Applicable.

         ITEM 11.          EXECUTIVE COMPENSATION

                           Not Applicable.

         ITEM 12.          SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND
                           MANAGEMENT AND RELATED STOCKHOLDER MATTERS

                           (a)  Securities Authorized For Issuance Under
                                Equity Compensation Plans: None.
                           (b)  Security Ownership Of Certain Beneficial
                                Owners: None.
                           (c)  Security Ownership Of Management: Not
                                Applicable.
                           (d)  Changes In Control: None.

         ITEM 13.          CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

                           None.

         ITEM 14.          PRINCIPAL ACCOUNTING FEES AND SERVICES

                           Not Applicable.

                                       4
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         PART IV

         ITEM 15.          EXHIBITS, FINANCIAL STATEMENT SCHEDULES

                           (a)(1)   Financial Statements: Not Applicable

                           (a)(2)   Financial Statement Schedules: Not
                                    Applicable

                           (a)(3)   List of Exhibits

                           The following exhibits are filed as part of, and
                           incorporated by reference into this Annual Report on
                           Form 10-K:

                                    31.1     Certification of President of
                                             Registrant dated March 29, 2005,
                                             pursuant to Rules 13a-14 and 15d-14
                                             under the Securities Exchange Act
                                             of 1934, as adopted pursuant to
                                             Section 302 of the Sarbanes-Oxley
                                             Act of 2002, with respect to the
                                             Registrant's Annual Report on Form
                                             10-K for the year ended December
                                             31, 2004.

                                    99.1     Trustee's Annual Compliance
                                             Certificate dated March 24, 2005.

                                    99.2     Report of Deloitte & Touche LLP,
                                             Independent Registered Public
                                             Accounting Firm dated March 25,
                                             2005, Registrant's Assertion on
                                             Compliance with PPLUS Minimum
                                             Servicing Standards dated March 25,
                                             2005 and PPLUS Minimum Servicing
                                             Standards.

                                    99.3     Report of Ernst & Young LLP,
                                             Independent Registered Public
                                             Accounting Firm dated March 14,
                                             2005, The Bank of New York's
                                             Assertion on Compliance with PPLUS
                                             Minimum Servicing Standards dated
                                             March 14, 2005 and PPLUS Minimum
                                             Servicing Standards.

                           (b)      Exhibits

                                    The Registrant hereby files as part of this
                                    Annual Report on Form 10-K the exhibits
                                    listed in Item 15(a)(3) set forth above.

                           (c)      Financial Statement Schedules

                                    Not applicable.


                                       5
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                                   SIGNATURES

                  Pursuant to the requirements of Section 13 or 15(d) 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: March 29, 2005                        By:    /s/ Stephan Kuppenheimer
                                               ---------------------------------
                                                 Name:    Stephan Kuppenheimer
                                                 Title:   President