UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-K

(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, 2006
                                       or
|_| TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES
   EXCHANGE ACT OF 1934
For Transition period ______________________________


             Commission File Number of issuing entity: 333-131209-02
                           RASC SERIES 2006-EMX4 TRUST
           (Exact name of issuing entity as specified in its charter)

                    RESIDENTIAL ASSET SECURITIES CORPORATION
              (Exact name of depositor as specified in its charter)

                        RESIDENTIAL FUNDING COMPANY, LLC
               (Exact name of sponsor as specified in its charter)

                                    New York
                       ------------------------ ---------
      (State or other jurisdiction of incorporation or organization of the
                                 issuing entity)

            c/o Residential Funding Company, LLC, as Master Servicer
                         8400 Normandale Lake Boulevard
                          Minneapolis, Minnesota 55437

           (Address of principal executive offices of issuing entity)

             (952) 857-7000 (Telephone number, including area code)

                                      None
                      (I.R.S. Employer Identification No.)

                                       N/A
           (Former name, former address, if changed since last report)

Securities  registered  pursuant to Section  12(b) of the Act:  None  Securities
Registered  pursuant to Section 12(g) of the Act: None 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 Section 15(d) of the Act.

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Yes |X|  No  |_|
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.
|X| Yes           |_| 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 II of the Form 10-K or any  amendment to this
Form 10-K. |X| [Item 405 of Regulation S-K is not applicable.] 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| Registrant has no voting or non-voting  common
equity outstanding held by non-affiliates.


<PAGE>


                                     PART I

THE FOLLOWING ITEMS HAVE BEEN OMITTED IN ACCORDANCE  WITH GENERAL  INSTRUCTION J
TO FORM 10-K:

Item 1: Business.
Item 1A: Risk Factors.
Item 2: Properties.
Item 3: Legal Proceedings.
Item 4: Submission of Matters to a Vote of Security Holders.

ITEM 1B. UNRESOLVED STAFF COMMENTS.

Not Applicable.

SUBSTITUTE INFORMATION PROVIDED IN ACCORDANCE WITH GENERAL INSTRUCTION J TO FORM
10-K:

ITEM 1112(B) OF REGULATION AB. SIGNIFICANT OBLIGORS OF POOL ASSETS
(FINANCIAL INFORMATION).

None.

ITEM 1114(B)(2) OF REGULATION AB: CREDIT ENHANCEMENT AND OTHER SUPPORT,
EXCEPT FOR CERTAIN DERIVATIVES INSTRUMENTS (FINANCIAL INFORMATION).

None.

ITEM 1115(B) OF REGULATION AB: CERTAIN DERIVATIVES INSTRUMENTS (FINANCIAL
INFORMATION).

Based  on the  standards  set  forth  in  Item  1115(b)  of  Regulation  AB,  no
information is required in response to this Item.

ITEM 1117 OF REGULATION AB: LEGAL PROCEEDINGS.

There are no material pending legal or other proceedings  involving the mortgage
loans or Residential Funding Company,  LLC ("Residential  Funding"),  as sponsor
and master servicer,  Residential Asset Securities Corporation, as depositor, or
RASC Series 2006-EMX4 Trust, as the issuing entity,  or other parties  described
in Item 1117 of Regulation AB that, individually or in the aggregate, would have
a material  adverse impact on investors in the securities (the  "Securities") to
which this report relates.


<PAGE>

Residential  Funding is currently a party to various legal  proceedings  arising
from time to time in the ordinary course of its business,  some of which purport
to be class actions. Based on information currently available, it is the opinion
of Residential  Funding that the eventual outcome of any currently pending legal
proceeding,  individually or in the aggregate,  will not have a material adverse
effect on its ability to perform  its  obligations  in relation to the  mortgage
loans. No assurance, however, can be given that the final outcome of these legal
proceedings, if unfavorable,  either individually or in the aggregate, would not
have a material  adverse impact on  Residential  Funding.  Any such  unfavorable
outcome could adversely affect the ability of Residential Funding to perform its
servicing  duties with respect to the mortgage loans and potentially lead to the
replacement of Residential Funding with a successor servicer.

Mortgage Lenders Network USA, Inc. ("MLN") was subservicer of the mortgage loans
during the period  covered by this report on Form 10-K. On February 5, 2007, MLN
filed bankruptcy under Chapter 11 in the United States  Bankruptcy Court for the
District  of Delaware  and  immediately  began the  process of winding  down its
remaining servicing business.  Servicing responsibilities for all mortgage loans
subserviced by MLN for the Issuing Entity were  transferred to Wells Fargo Bank,
National  Association  ("Wells  Fargo") on March 1, 2007.  Wells Fargo meets the
standards set forth in Residential Funding's servicing guidelines.

                                     PART II

THE FOLLOWING ITEMS HAVE BEEN OMITTED IN ACCORDANCE  WITH GENERAL  INSTRUCTION J
TO FORM 10-K:

Item 5:  Market for Registrant's Common Equity, Related Stockholder Matters
         and Issuer Purchases of Equity Securities.
Item 6:  Selected Financial Data.
Item 7:  Management's Discussion and Analysis of Financial Condition and
         Results of Operations.
Item 7A: Quantitative and Qualitative Disclosures about Market Risk.
Item 8:  Financial Statements and Supplementary Data.
Item 9:  Changes in and Disagreements with Accountants on Accounting and
         Financial Disclosure.
Item 9A: Controls and Procedures.

ITEM 9B: OTHER INFORMATION.

None.

                                    PART III

THE FOLLOWING ITEMS HAVE BEEN OMITTED IN ACCORDANCE  WITH GENERAL  INSTRUCTION J
TO FORM 10-K:

Item 10: Directors and Executive Officers of the Registrant.
Item 11: Executive Compensation.
Item 12: Security Ownership of Certain Beneficial Owners and Management and
         Related Stockholder Matters.
Item 13: Certain Relationships and Related Transactions.
Item 14: Principal Accountant Fees and Services.


<PAGE>

SUBSTITUTE INFORMATION PROVIDED IN ACCORDANCE WITH GENERAL INSTRUCTION J TO FORM
10-K:

ITEM 1119 OF REGULATION AB:  AFFILIATIONS AND CERTAIN RELATIONSHIPS AND
RELATED TRANSACTIONS.

Information  contemplated  by Item 1119 of  Regulation  AB has been omitted from
this report in reliance on the Instruction to Item 1119.

ITEM 1122 OF REGULATION AB: COMPLIANCE WITH APPLICABLE SERVICING CRITERIA.

Each of Residential  Funding Company,  LLC,  Mortgage Lenders Network USA, Inc.,
U.S. Bank National  Association and Wells Fargo Bank,  National  Association (in
its capacity as custodian) (each, a "Servicing Participant") has been identified
by the registrant as a party  participating in the servicing function during the
period  covered by this Form 10-K with  respect to the pool  assets  held by the
Issuing Entity.  Each of Residential  Funding  Company,  LLC, U.S. Bank National
Association and Wells Fargo Bank, National Association has completed a report on
an  assessment  of compliance  with the  servicing  criteria  applicable to such
Servicing  Participant  (each, a "Report on Assessment") as of December 31, 2006
and for the period  covered by this Form 10-K,  which Reports on Assessment  are
attached  as  exhibits  to this Form  10-K.  In  addition,  each such  Servicing
Participant has provided an attestation  report (each, an "Attestation  Report")
by a registered  independent public accounting firm regarding its related Report
on Assessment.  Each  Attestation  Report is attached as an exhibit to this Form
10-K.  As  discussed in more detail below under  "--Missing  Report,"  under the
terms of its  servicing  agreement,  Mortgage  Lenders  Network  USA,  Inc.  was
obligated,  but  failed,  to  deliver  a Report  on  Assessment  and  associated
Attestation Report.

A Servicing  Participant may engage one or more vendors to perform  specific and
limited,  or scripted  activities  that  address all or a portion of one or more
servicing criteria applicable to such Servicing Participant. In these cases, the
Servicing  Participant has instituted policies and procedures to monitor whether
such vendors'  activities  comply in all material  respects with such  servicing
criteria, and may elect to take responsibility for assessing compliance with the
servicing  criteria  applicable  to such vendors'  activities in such  Servicing
Participant's Report on Assessment.

Except as disclosed below, no Report on Assessment or related Attestation Report
has identified  (i) any material  instance of  noncompliance  with the servicing
criteria  identified  in such Report on  Assessment as applicable to the related
Servicing  Participant  or  (ii)  any  material  deficiency  in  such  Servicing
Participant's policies and procedures to monitor vendor compliance.

Exceptions:

Residential  Funding  Company,   LLC:  The  Report  on  Assessment  prepared  by
Residential  Funding  Company,  LLC  and the  related  Attestation  Report  have
identified material noncompliance with one servicing criterion applicable to it.
Specifically,   with  regard  to  servicing  criterion  1122(d)(3)(i)(B)  (which
contemplates  that  reports  to  investors  provide  information  calculated  in
accordance with the terms specified in the transaction agreements),  information
required  by the  transaction  agreements  was  excluded  from,  or  incorrectly
reported in, certain of the investor  reports.  The registrant  does not believe
these  reporting  errors had any material  impacts or effects on  investors  and
corrective action was completed to address ongoing compliance.


<PAGE>

Missing Report:

Mortgage  Lenders  Network USA,  Inc.:  As  discussed  above under "Item 1117 of
Regulation AB: Legal  Proceedings,"  Mortgage  Lenders Network USA, Inc. ("MLN")
was  subservicer  of the mortgage loans during the period covered by this report
on Form 10-K,  but was  replaced by Wells Fargo Bank,  National  Association  on
March 1, 2007.

On February 5, 2007, MLN filed  bankruptcy under Chapter 11 in the United States
Bankruptcy Court for the District of Delaware and immediately  began the process
of  winding  down its  remaining  servicing  business.  Under  the  terms of its
servicing  agreement,  MLN was  obligated,  but  failed,  to deliver a Report on
Assessment  and  associated  Attestation  Report on or before March 1, 2007. The
registrant has asked MLN to honor its  contractual  commitment and deliver these
reports but MLN has not complied with the request.  None of Residential  Funding
Company, LLC, Residential Asset Securities Corporation, or RASC Series 2006-EMX4
Trust is an affiliate of MLN.

Platform-Level Reports:

Regulations of the Securities and Exchange  Commission  (the "SEC") require that
each  Servicing  Participant  complete a Report on  Assessment  at a  "platform"
level,  meaning that the transactions covered by the Report on Assessment should
include  all  asset-backed  securities  transactions  involving  such  Servicing
Participant  that are backed by the same asset type.  More recent  guidance from
the SEC staff identifies additional parameters which a Servicing Participant may
apply to define  and  further  limit its  platform.  For  example,  a  Servicing
Participant  may define its  platform  to include  only  transactions  that were
completed  on or after  January  1, 2006 and that were  registered  with the SEC
pursuant  to  the  Securities  Act  of  1933.  Each  Servicing   Participant  is
responsible  for defining its own platform,  and each  platform  will  naturally
differ based on various factors,  including the Servicing Participant's business
model and the transactions in which it is involved.

Based on our understanding of their platforms and the guidance that is available
at this time, we believe that the parameters by which the Servicing Participants
have defined their platforms should be permissible.  However,  because the SEC's
regulations  are new and the guidance  that is available at this time is subject
to clarification or change, we cannot assure you that the SEC and its staff will
necessarily agree.

ITEM 1123 OF REGULATION AB: SERVICER COMPLIANCE STATEMENT.

Each of Residential Funding Company,  LLC and Mortgage Lenders Network USA, Inc.
(each,  a "Servicer")  has been  identified by the registrant as a servicer with
respect to the pool  assets  held by the  Issuing  Entity.  Residential  Funding
Company,  LLC has provided a statement of compliance with its obligations  under
the servicing  agreement  applicable to it (a  "Compliance  Statement")  for the
period covered by this Form 10-K.  Residential Funding Company, LLC's Compliance
Statement is attached as an exhibit to this Form 10-K and has not identified any
instance  where it has failed to fulfill its  obligations  under the  applicable
servicing agreement in any material respects.

As discussed  above, on February 5, 2007, MLN filed  bankruptcy under Chapter 11
in the  United  States  Bankruptcy  Court  for  the  District  of  Delaware  and
immediately began the process of winding down its remaining  servicing business.
Under the terms of its servicing  agreement,  MLN was obligated,  but failed, to
deliver a Compliance  Statement on or before March 1, 2007.  The  registrant has
asked  MLN to honor its  contractual  commitment  and  deliver  this  Compliance
Statement but MLN has not complied with the request.


                                     PART IV

ITEM 15.    EXHIBITS, FINANCIAL STATEMENT SCHEDULES.

      (a)(1) Not Applicable.

      (a)(2) Not Applicable.

      (a)(3) Not Applicable.

      (b) Exhibits.


<PAGE>

EXHIBIT
NUMBER                                  DESCRIPTION
----------   ------------------------------------------------------------------
3.1          Certificate  of  Incorporation  of  Residential   Asset  Securities
             Corporation (incorporated by reference to the Annual Report on Form
             10-K for the period ended  December 31, 2006,  filed by RASC Series
             2006-KS1 Trust with the Securities and Exchange Commission).
3.2          Bylaws of Residential Asset Securities Corporation (incorporated by
             reference  to the Annual  Report on Form 10-K for the period  ended
             December 31,  2006,  filed by RASC Series  2006-KS1  Trust with the
             Securities and Exchange Commission).
10.1         Pooling and  Servicing  Agreement,  dated as of May 1, 2006, by and
             among  Residential  Asset  Securities  Corporation,  as  depositor,
             Residential  Funding  Company,  LLC (formerly  Residential  Funding
             Corporation),   as  master   servicer,   and  U.S.   Bank  National
             Association, as trustee (incorporated by reference to the Report on
             Form 8-K  filed by the  Issuing  Entity  with  the  Securities  and
             Exchange Commission on June 9, 2006).
10.2         Assignment  and  Assumption  Agreement,  dated as of May 25,  2006,
             between  Residential  Funding  Company,  LLC (formerly  Residential
             Funding  Corporation) and Residential Asset Securities  Corporation
             (incorporated  by  reference to the Report on Form 8-K filed by the
             Issuing Entity with the Securities and Exchange  Commission on June
             9, 2006).
10.3         Confirmation,  dated as of May 25, 2006, between U.S. Bank National
             Association,  as  trustee  on behalf of the RASC  Series  2006-EMX4
             Trust,  and  Deutsche  Bank AG, New York  Branch  (incorporated  by
             reference  to the  Report on Form 8-K filed by the  Issuing  Entity
             with the Securities and Exchange Commission on June 9, 2006).
31.1         Certification of Residential Funding Company,  LLC pursuant to Rule
             13a-14(d)/15d-14(d) under the Securities Exchange Act of 1934.
33.1         Report on  Assessment  of  Compliance  with  Servicing  Criteria of
             Residential  Funding  Company,  LLC as of December 31, 2006 and for
             the period covered by this Form 10-K.
33.2         Report on Assessment of Compliance with Servicing  Criteria of U.S.
             Bank  National  Association  as of  December  31,  2006 and for the
             period covered by this Form 10-K.
33.3         Report on Assessment of Compliance with Servicing Criteria of Wells
             Fargo Bank,  National  Association  as of December 31, 2006 and for
             the period covered by this Form 10-K.
34.1         Attestation Report of  PricewaterhouseCoopers  LLP on Assessment of
             Compliance with Servicing Criteria relating to Residential  Funding
             Company, LLC.
34.2         Attestation Report of Ernst & Young, LLP on Assessment of
             Compliance with Servicing Criteria relating to U.S. Bank
             National Association.
34.3         Attestation Report of KPMG, LLP on Assessment of Compliance with
             Servicing Criteria relating to Wells Fargo Bank, National
             Association.
35.1         Servicer Compliance Statement of Residential Funding Company,
             LLC.

      (c) 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 26, 2007
                                        RASC SERIES 2006-EMX4 TRUST

                                        By:  Residential Funding Company,
                                            LLC,
                                              as Master Servicer

                                              By:  /s/ Anthony N.  Renzi
                                                  Name: Anthony N. Renzi
                                                  Title: Managing Director





<PAGE>


                                INDEX TO EXHIBITS

EXHIBIT
NUMBER                                  DESCRIPTION
----------   ------------------------------------------------------------------
3.1          Certificate  of  Incorporation  of  Residential   Asset  Securities
             Corporation (incorporated by reference to the Annual Report on Form
             10-K for the period ended  December 31, 2006,  filed by RASC Series
             2006-KS1 Trust with the Securities and Exchange Commission).
3.2          Bylaws of Residential Asset Securities Corporation (incorporated by
             reference  to the Annual  Report on Form 10-K for the period  ended
             December 31,  2006,  filed by RASC Series  2006-KS1  Trust with the
             Securities and Exchange Commission).
10.1         Pooling and  Servicing  Agreement,  dated as of May 1, 2006, by and
             among  Residential  Asset  Securities  Corporation,  as  depositor,
             Residential  Funding  Company,  LLC (formerly  Residential  Funding
             Corporation),   as  master   servicer,   and  U.S.   Bank  National
             Association, as trustee (incorporated by reference to the Report on
             Form 8-K  filed by the  Issuing  Entity  with  the  Securities  and
             Exchange Commission on June 9, 2006).
10.2         Assignment  and  Assumption  Agreement,  dated as of May 25,  2006,
             between  Residential  Funding  Company,  LLC (formerly  Residential
             Funding  Corporation) and Residential Asset Securities  Corporation
             (incorporated  by  reference to the Report on Form 8-K filed by the
             Issuing Entity with the Securities and Exchange  Commission on June
             9, 2006).
10.3         Confirmation,  dated as of May 25, 2006, between U.S. Bank National
             Association,  as  trustee  on behalf of the RASC  Series  2006-EMX4
             Trust,  and  Deutsche  Bank AG, New York  Branch  (incorporated  by
             reference  to the  Report on Form 8-K filed by the  Issuing  Entity
             with the Securities and Exchange Commission on June 9, 2006).
31.1         Certification of Residential Funding Company,  LLC pursuant to Rule
             13a-14(d)/15d-14(d) under the Securities Exchange Act of 1934.
33.1         Report on  Assessment  of  Compliance  with  Servicing  Criteria of
             Residential  Funding  Company,  LLC as of December 31, 2006 and for
             the period covered by this Form 10-K.
33.2         Report on Assessment of Compliance with Servicing  Criteria of U.S.
             Bank  National  Association  as of  December  31,  2006 and for the
             period covered by this Form 10-K.
33.3         Report on Assessment of Compliance with Servicing Criteria of Wells
             Fargo Bank,  National  Association  as of December 31, 2006 and for
             the period covered by this Form 10-K.
34.1         Attestation Report of  PricewaterhouseCoopers  LLP on Assessment of
             Compliance with Servicing Criteria relating to Residential  Funding
             Company, LLC.
34.2         Attestation Report of Ernst & Young, LLP on Assessment of
             Compliance with Servicing Criteria relating to U.S. Bank
             National Association.
34.3         Attestation Report of KPMG, LLP on Assessment of Compliance with
             Servicing Criteria relating to Wells Fargo Bank, National
             Association.
35.1         Servicer Compliance Statement of Residential Funding Company,
             LLC.





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