ASSIGNMENT AGREEMENT

                                 EXHIBIT 99.4
                                 ------------

                           The Assignment Agreement


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                             ASSIGNMENT AGREEMENT


      ASSIGNMENT AGREEMENT, dated as of November 15, 2006 ("Assignment
Agreement"), among COUNTRYWIDE HOME LOANS, INC. ("Assignor"), THE BANK OF NEW
YORK ("Assignee"), not in its individual or corporate capacity but solely as
Swap Contract Administrator for Alternative Loan Trust 2006-OA18, pursuant to
a Swap Contract Administration Agreement (the "Swap Contract Administration
Agreement") dated as of November 15, 2006, and DEUTSCHE BANK AG, NEW YORK
BRANCH ("Remaining Party").

                             W I T N E S S E T H:
                             - - - - - - - - - -

      WHEREAS, effective as of November 15, 2006, Assignor desires to assign
all of its rights and delegate all of its duties and obligations to Assignee
under a certain Transaction (the "Assigned Transaction") as evidenced by a
certain confirmation with a Trade Date of November 3, 2006, whose DEUTSCHE
BANK AG, NEW YORK BRANCH reference number is Global No. N530435N (the
"Confirmation"), a copy of which is attached hereto as Exhibit I;

      WHEREAS, Assignor and Remaining Party executed and delivered the
Confirmation in connection with, and as part of, the ISDA Master Agreement
dated as of July 18, 1996, as amended or supplemented from time to time (the
"Old Master Agreement"), between Assignor and Remaining Party;

      WHEREAS, Assignee desires to accept the assignment of rights and assume
the delegation of duties and obligations of the Assignor under the Assigned
Transaction and the Confirmation, including any modifications that may be
agreed to by Assignee and Remaining Party; and

      WHEREAS, Assignor desires to obtain the written consent of Remaining
Party to the assignment, delegation and assumption, and Remaining Party
desires to grant such consent in accordance with the terms hereof.

      NOW, THEREFORE, in consideration of the premises and of the mutual
agreements herein contained and for good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged, the parties agree as
follows:

      1.    Assignment and Assumption. Effective as of and from November 15,
2006 (the "Effective Date"), Assignor hereby assigns all of its rights and
delegates all of its duties and obligations to Assignee, and Assignee hereby
assumes all Assignor's rights, duties, and obligations, under the Assigned
Transaction and the Confirmation arising on or after the Effective Date.

      2.    Release. Effective as of and from the Effective Date, Remaining
Party and Assignor hereby release one another from all duties and obligations
owed under and in respect of the Assigned Transaction and the Confirmation,
and Assignor hereby terminates its rights under and in respect of the Assigned
Transaction.


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      3.    Limitation on Liability. Assignor and Remaining Party agree to the
following: (a) The Bank of New York ("BNY") is entering into this Assignment
Agreement not in its individual or corporate capacity, but solely in its
capacity as Swap Contract Administrator under the Swap Contract Administration
Agreement; (b) in no case shall BNY (or any person acting as successor Swap
Contract Administrator under the Swap Contract Administration Agreement) be
personally liable for or on account of any of the statements, representations,
warranties, covenants or obligations stated t