SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    ----------
                                    FORM 10-K

                        FOR ANNUAL AND TRANSITION REPORTS
                     PURSUANT TO SECTIONS 13 OR 15(D) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


(Mark One)
[X]      ANNUAL REPORT PURSUANT TO SECTION 13 or 15(d) OF THE SECURITIES
         EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2005
                          -----------------

                                       OR

[  ]     TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
         EXCHANGE  ACT OF 1934

For the transition period from __________ to __________

                  COMMISSION FILE NUMBERS 333-101155, 001-32424


                            MS STRUCTURED ASSET CORP.
                                  ON BEHALF OF
                            SATURNS TRUST NO. 2005-2
             (Exact name of registrant as specified in its charter)


                     Delaware                                    13-4026700
(State or other jurisdiction of incorporation                  (IRS Employer
                or organization)                             Identification No.)




             1585 BROADWAY, SECOND FLOOR
             NEW YORK, NEW YORK                          10036
             ATTENTION: MADHU PHILIPS
      (Address of principal executive office)          (Zip Code)

Registrant's telephone number, including area code:   (212) 761-2520

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

   Title of Each Class                 Name of Each Exchange on Which Registered
   SATURNS AON CAPITAL SECURITY              NEW YORK STOCK EXCHANGE
   BACKED SERIES 2005-2 CLASS
   A CALLABLE UNITS


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

                                      NONE


<PAGE>
         Indicate by check mark if the registrant is a well-known seasoned
issuer, as defined in Rule 405 of the Securities Act.  Yes        No  X
                                                          -----     -----

         Indicate by check mark if the registrant is not required to file
reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.
Yes        No  X
   -----     -----

         Indicate by check mark whether 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 a large accelerated
filer, an accelerated filer, or a non-accelerated filer. See definition of
"accelerated filer and large accelerated filer" in Rule 12b-2 of the Exchange
Act.

(Check one):

Large accelerated filer       Accelerated filer       Non-accelerated filer  X
                        ---                     ---                         ---

         Indicate by check mark whether the registrant is a shell company (as
defined in Rule 12b-2 of the Act).  Yes        No  X
                                       -----     -----

         All of the common stock of the registrant is held by Morgan Stanley.

         Indicate by check mark whether the registrant has filed all documents
and reports required to be filed by Section 12, 13 or 15(d) of the Securities
Exchange Act of 1934 subsequent to the distribution of securities under a plan
confirmed by a court. Yes        No
                          -----     -----

         As of February 20, 2006, 1,000 shares of common stock, par value $1.00
per share, were outstanding.

                      DOCUMENTS INCORPORATED BY REFERENCE:

The distribution reports to security holders filed on Form 8-K during the Fiscal
Year in lieu of reports on Form 10-Q.

                                Introductory Note

The Registrant is the depositor under the trust agreements for it various
SATURNS Units listed on the New York Stock Exchange. The Units do not represent
obligations of or interests in the Depositor. Pursuant to staff administrative
positions established in various no-action letters, see e.g. Corporate Asset
Backed Corporation (available August 9, 1995), the Registrant is not required to
respond to various items of Form 10-K. Such items are designated herein as "Not
applicable." Distribution reports detailing receipts and distributions by each
trust are filed shortly after each distribution date on Form 8-K in lieu of
reports on Form 10-Q.

The underlying security issuer or guarantor, as applicable, of the securities
held by each of the trusts is subject to the informational requirements of the
Exchange Act. The underlying security issuer or guarantor, as applicable,
currently files reports, proxy statements and other information with the SEC.
For information regarding such underlying security issuer or guarantor, you
should refer to such reports. These periodic, current and other reports and
other information can be inspected and copied at the public reference facilities
maintained by the SEC at Room 1024, 100 F Street, N.E., Washington, D.C. 20549.
Copies of those materials can be obtained by making a written request to the
SEC, Public Reference Section, 100 F Street, N.E., Washington, D.C. 20549, at
prescribed rates. The SEC also maintains a website on the internet at
http://www.sec.gov at which users can view and download copies of reports,
proxy, information statements and other information filed electronically. In
addition, those reports and other information may also be obtained from the
underlying security issuer by making a request to the underlying security
issuer. The trust, the trustee, the Registrant, and their affiliates have not
verified, have not undertaken to verify, and will not verify, the content of any
such reports or information. The name and the central index key (CIK) for each
underlying security issuer or guarantor is set forth below:

<TABLE>
<CAPTION>
     Trust             Underlying Security Issuer or Guarantor             CIK
<S>           <C>                                                     <C>
2005-2        Aon Corporation                                         0000315293
</TABLE>
<PAGE>


                                     PART I

ITEM 1.  BUSINESS

         Not Applicable

ITEM 2.  PROPERTIES

         Not Applicable

ITEM 3.  LEGAL PROCEEDINGS

         None

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

         None


                                     PART II

ITEM 5.  MARKET FOR REGISTRANT'S COMMON EQUITY AND RELATED STOCKHOLDER MATTERS

The Units issued by the SATURNS trusts listed below representing investors'
interest in such trust are represented by one or more physical certificates
registered in the name of Cede & Co., the nominee of The Depository Trust
Company. The Units are listed on the New York Stock Exchange:

SATURNS Trust No. 2005-2 Class A Units (Aon Capital Security Backed )


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


<PAGE>


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

         Not Applicable

                                    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

         None

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

         None

ITEM 14. PRINCIPAL ACCOUNTING FEES AND SERVICES

         Not Applicable

                                     PART IV

ITEM 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K

         (a) The following documents are filed as part of this Report: None

         (b) Reports on Form 8-K:


<PAGE>


See Table Below:

<TABLE>
<CAPTION>
 SATURNS Trust No.:        Closing Date              Payment Dates              Form 8-K Filing Dates (Not Trust
                                                                              Agreement Filings in connection with
                                                                                          Closing Date)

                                                                                           For FY 2005
<S>                    <C>                   <C>                             <C>
2005-2                 1/27/05               January 1 and July 1,           July 12, 2005
                                             commencing on July 1, 2005
</TABLE>

         (c) Exhibits:

Exhibit 23        Consent of Pustorino, Puglisi & Co., LLP (See Exhibit 99.1--
                  contained in final paragraph of accountants' letter)
Exhibit 31.1      Rule 13a-14(d) Certification
Exhibit 31.2      Trustee Compliance Certification
Exhibit 99.1      Report of Pustorino, Puglisi & Co., LLP

         (d) Not applicable


<PAGE>


                                   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, thereunto duly authorized.



         Date:  March 29, 2006

                                            MS STRUCTURED ASSET CORP.
                                            (Registrant)



                                            By:       /s/ Madhu Philips
                                            ---------------------------------
                                            Name:     Madhu Philips
                                            Title:    Vice President


<PAGE>


                                                                      Exhibit 23
                   [Consent of Pustorino, Puglisi & Co., LLP]



<PAGE>


                                                                    Exhibit 31.1
                                  CERTIFICATION

I, Madhu Philips, certify that:

1. I have reviewed this annual report on Form 10-K, and all reports on Form 8-K
containing distribution or servicing reports filed in respect of periods
included in the year covered by this annual report, of MS Structured Asset Corp.
on behalf of SATURNS Trust No. 2005-2;

2. Based on my knowledge, the information in these reports, taken as a whole,
does not contain any untrue statement of a material fact or omit to state a
material fact necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading as of the
last day of the period covered by this annual report;

3. Based on my knowledge, the distribution or servicing information required to
be provided to the depositor by the trustee under the pooling and servicing, or
similar, agreement, for inclusion in these reports is included in these reports;

4. I am responsible for reviewing the activities performed by the depositor and
the trustee under the pooling and servicing, or similar, agreement and based
upon my knowledge and the annual compliance review required under that
agreement, and except as disclosed in the reports, the depositor and trustee
have each fulfilled its obligations under that agreement; and

5. The reports disclose all significant deficiencies relating to the compliance
by the trustee and the depositor with the minimum servicing or similar standards
based upon the report provided by an independent public accountant, after
conducting a review in compliance with the Uniform Single Attestation Program
for Mortgage Bankers or similar procedure, as set forth in the pooling and
servicing, or similar, agreement, that is included in these reports.

In giving the certifications above, I have reasonably relied on information
provided to me by the following unaffiliated parties: LaSalle Bank National
Association and its officers and agents.



                                            By:       /s/ Madhu Philips
                                            ---------------------------------
                                            Name:     Madhu Philips
                                            Title:    Vice President
                                            Date:     March 15, 2006


<PAGE>


                                                                    Exhibit 31.2
                             COMPLIANCE CERTIFICATE

                  In connection with the preparation and delivery of the annual
report on Form 10-K of MS Structured Asset Corp. on behalf of SATURNS Trust No.
2005-2 for the fiscal year ending December 31, 2005, and the certifications
given by Madhu Philips with respect thereto, the undersigned hereby certifies
that she is a duly elected Vice President of LaSalle Bank National Association
and further certifies in her capacity as such as follows:


1. LaSalle Bank National Association has prepared all distribution reports with
respect to each distribution date for SATURNS Trust No. 2005-2, and has filed a
copy of such reports on Form 8-K during the fiscal year as described on Exhibit
A hereto.

2. I have reviewed all reports on Form 8-K containing distribution reports filed
in respect of periods included in the fiscal year covered by the annual report
of MS Structured Asset Corp. on behalf of SATURNS Trust No. 2005-2;

3. I am familiar with the operations of LaSalle Bank National Association with
respect to the SATURNS program and SATURNS Trust No. 2005-2 and the requirement
imposed by the applicable trust agreement;

4. Based on my knowledge, the information in the distribution reports, taken as
a whole, does not contain any untrue statement of a material fact or omit to
state a material fact necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading as of the
last day of the period covered by the annual report;

5. Based on my knowledge, the information required to be provided under each
trust agreement, for inclusion in these reports, is included in these reports;

6. Based on my knowledge, and except as disclosed in the reports, the trustee
has fulfilled its obligations, including any servicing obligations, under the
trust agreement.

7. Based on my knowledge, and except as disclosed in the reports, there are no
material legal proceedings with respect to any trust, involving the trust or
LaSalle Bank National Association as trustee.


                                            By:      /s/ Barbara L. Marik
                                            ---------------------------------
                                            Name:    Barbara L. Marik
                                            Title:   First Vice President
                                            Date:    March 22, 2006


<PAGE>


                                                                       EXHIBIT A


<TABLE>
<CAPTION>
 SATURNS Trust No.:        Closing Date             Payment Dates                                  Form 8-K Filing Dates (Not Trust
                                                                                                    Agreement Filings in connection
                                                                                                          with Closing Date)

                                                                                                             For FY 2005
 <S>                       <C>                   <C>                                               <C>
 2005-2                    1/27/05               January 1 and July 1,                             July 12, 2005
                                                 commencing on July 1, 2005
</TABLE>


<PAGE>


                                                                    Exhibit 99.1
                    [Report of Pustorino, Puglisi & Co., LLP]



<PAGE>


                  [On Pustorino, Puglisi & Co., LLP Letterhead]





                         INDEPENDENT ACCOUNTANT'S REPORT
                       ON APPLYING AGREED-UPON PROCEDURES



LaSalle Bank National Association
135 S. LaSalle Street, Suite 1625
Chicago, IL 60603

MS Structured Asset Corp.
1585 Broadway
New York, NY 10036


With respect to the "Structured Asset Trust Unit Repackagings 2005-2" (SATURNS
Trust 2005-2) we have performed the procedures listed below, which were agreed
to by LaSalle Bank National Association (the Trustee) and MS Structured Asset
Corp. (the Depositor) solely to assist the Depositor in evaluating the Trustee's
assertions that the administration of the Trust Property of SATURNS Trust 2005-2
(the Trust) was conducted in accordance with the terms of the Trust Agreement
relating thereto for the period January 27, 2005 (date of inception) through
December 31, 2005 This agreed-upon procedures engagement was performed in
accordance with attestation standards established by the American Institute of
Certified Public Accountants. The sufficiency of these procedures is solely the
responsibility of the specified users of this report, the Trustee and the
Depositor. Consequently, we make no representation regarding the sufficiency of
the procedures described below either for the purpose for which this report has
been requested or for any other purpose. Pursuant to the foregoing, for SATURNS
Trust 2005-2, we:

1.       Calculated the semi-annual interest payment, on the underlying security
         as defined in the prospectus.

2.       Verified that interest payments on the underlying security were
         received on the scheduled date for payment thereof.

3.       Calculated the semi-annual interest distributions and principal
         distributions, if any, on the Class A and Class B units.


<PAGE>

                                       -2-


4.       Verified that distributions on Class A and Class B units were made on
         the scheduled dates for distribution thereof.

5.       Verified Trust property amounts and balances.

6.       Verified that the amounts of any units redeemed, upon receipt of
         redemption payments or notices of exercise of warrants, matched amounts
         of the relevant redemptions and warrant exercise amounts notified to
         the Trustee.

7.       Verified that the proceeds of redemptions, exercise of warrants and
         liquidation of underlying securities following any underlying security
         default were applied within the time and in the manner provided in the
         Trust Agreement.

8.       Verified that reports on Form 8-K were filed by the Trustee with the
         Securities and Exchange Commission on or before the fifteenth day
         following each payment date for the Class A and Class B units.

We were not engaged to, and did not, perform an examination, the objective of
which would be the expression of an opinion on the Trustee's assertions.
Accordingly, we do not express such an opinion. Had we performed additional
procedures, other matters might have come to our attention that would have been
reported to you.

We are independent public accountants with respect to the Trustee and the Trust,
as defined under the Code of Professional Ethics of the American Institute of
Certified Public Accountants.

This report is intended solely for the use of the Depositor and the Trustee and
should not be used by those who have not agreed to the procedures and taken
responsibility for the sufficiency of the procedures for their purposes.
However, this report is a matter of public record as a result of being included
as an exhibit to the annual report on Form 10-K prepared by MS Structured Asset
Corp. and filed with the Securities and Exchange Commission on behalf of SATURN
Trust 2005-2, and its distribution is not limited.



/s/ Pustorino, Puglisi & Co., LLP
---------------------------------
Pustorino, Puglisi & Co., LLP
New York, New York
March 1, 2006


<PAGE>


                    [On MS Structured Asset Corp. Letterhead]




March 13, 2006



Pustorino, Puglisi & Co., LLP
515 Madison Avenue
New York, NY 10022

Gentlemen:

In connection with your engagement to apply the agreed-upon procedures, as
listed in your engagement letters dated Janaury 26, 2006 and your reports dated
March 1, 2006, for the Trusts listed below:

o        SATURNS 2005-2
o        SATURNS 2005-3

We confirm, to the best of our knowledge and belief, the following
representations made to you during your engagement:

1.       We are responsible for the formulation of the assertion that the
         administration of the Trusts listed above was conducted in accordance
         with the terms of the individual Trust Agreements relating thereto for
         the 2005 dates of inception through December 31, 2005.

2.       There have been no fraudulent or other illegal acts that would have a
         material effect on the assertion.

3.       We have disclosed to you all known matters contradicting the assertion.

4.       There have been no communications from internal auditors and other
         independent practitioners or consultants relating to the assertions
         including communications received between December 31, 2005 and the
         date of this letter.

5.       We have made available to you all information that we believe is
         relevant to the assertion.

6.       We have responded fully to all inquiries made to us by you during the
         engagement.


<PAGE>

                                       -2-


7.       No events have occurred subsequent to December 31, 2005 that would
         require adjustment to or modification of the assertions.

8.       Your report is intended solely for the use of LaSalle Bank National
         Association (the Trustee) and MS Structured Asset Corp. (the Depositor)
         and should not be used by those who have not agreed to the procedures
         and taken responsibility for the sufficiency of the procedures for
         their purposes. We intend for the applicable reports to be a matter of
         public record as a result of their being included as an exhibit to the
         annual report on Form 10-K prepared by MS Structured Assets Corp. and
         filed with the Securities and Exchange Commission on behalf of the
         corresponding trusts.




  /s/ Madhu Philips
--------------------------
Signature


  Authorized Signatory
--------------------------
Title


  March 13, 2006
--------------------------
Date


<PAGE>


                 [On LaSalle Bank, National Association. Letterhead]




March 6, 2006



Pustorino, Puglisi & Co., LLP
515 Madison Avenue
New York, NY 10022

Gentlemen:

In connection with your engagement to apply the agreed-upon procedures, as
listed in your engagement letters dated Janaury 26, 2006 and your reports dated
March 1, 2006, for the Trusts listed below:

o        SATURNS 2005-2
o        SATURNS 2005-3

We confirm, to the best of our knowledge and belief, the following
representations made to you during your engagement:

1.        We are responsible for the formulation of the assertion that the
          administration of the Trusts listed above was conducted in accordance
          with the terms of the individual Trust Agreements relating thereto for
          the 2005 dates of inception through December 31, 2005.

2.        There have been no fraudulent or other illegal acts that would have a
          material effect on the assertion.

3.        We have disclosed to you all known matters contradicting the
          assertion.

4.        There have been no communications from internal auditors and other
          independent practitioners or consultants relating to the assertions
          including communications received between December 31, 2005 and the
          date of this letter.

5.        We have made available to you all information that we believe is
          relevant to the assertion.

6.        We have responded fully to all inquiries made to us by you during the
          engagement.


<PAGE>

                                       -2-


7.       No events have occurred subsequent to December 31, 2005 that would
         require adjustment to or modification of the assertions.

8.       Your report is intended solely for the use of LaSalle Bank National
         Association (the Trustee) and MS Structured Asset Corp. (the
         Depositor) and should not be used by those who have not agreed to the
         procedures and taken responsibility for the sufficiency of the
         procedures for their purposes. We intend for the applicable reports to
         be a matter of public record as a result of their being included as an
         exhibit to the annual report on Form 10-K prepared by MS Structured
         Assets Corp. and filed with the Securities and Exchange Commission on
         behalf of the corresponding trusts.




  /s/ Andy Streepey
--------------------------
Signature


  Assistant Vice President
--------------------------
Title


  March 6, 2006
--------------------------
Date