<Page>
                                                                       EXHIBIT A

                   AMENDMENT TO INVESTMENT ADVISORY AGREEMENT

This Amendment to Investment Advisory Agreement (this "Amendment") amends the
Investment Advisory Agreement between ING Investment Management LLC ("IIM") and
ING Insurance Company of America, formerly known as Aetna Insurance Company of
America ("Client"). This Amendment is dated as of August 26, 2003.

1.  BACKGROUND. IIM and Client are parties to an Investment Advisory Agreement,
    dated March 31, 2001, as amended (the "Agreement"), pursuant to which IIM
    provides Client with certain investment advisory services. IIM and Client
    wish to clarify the limited circumstances under which IIM may have custody
    of Client funds or securities under the Agreement. Although the parties do
    not intend by this Amendment to address whether or not Original Mortgage
    Documents (as defined below) are in fact securities, it is the intention of
    IIM and Client that, except as may be otherwise agreed from time to time,
    IIM will not have actual or constructive custody of Client funds or
    securities other than Original Mortgage Documents.
2.  AMENDMENT TO SECTION 3 OF THE AGREEMENT. Section 3 of the Agreement is
    hereby amended to add the following to the end of such Section:
   "Notwithstanding anything to the contrary in this Section 3, except with
   regard such Original Mortgage Documents as are selected by IIM from time to
   time, and as may otherwise be agreed between IIM and Client:

    (a)   IIM shall not maintain physical custody of Client funds or securities;
          and
    (b)   IIM shall not have the power to direct any custodian or other third
          party to transfer Client funds or securities, except in the case of
          (i) transactions involving a delivery vs. payment or vice versa,
          (ii) free receipts into Client Accounts, (iii) transfers between
          Client's own accounts, (iv) transfers to satisfy margin or collateral
          calls by brokers or other counterparties, and (v) other transactions
          that would not reasonably be considered to result in actual or
          constructive custody of Client funds or securities.

   "Original Mortgage Documents" means original (a) mortgage notes,
   (b) certificates of participation where more than one entity has invested in
   the mortgage via a participation agreement, and (c) letters of credit, as
   applicable, that are provided from time to time by borrowers as additional
   security."
3.  AMENDMENT TO SECTION 6 OF THE AGREEMENT. The second sentence of Section 6 of
    the Agreement is hereby amended to add the language highlighted in italics
    below:
   "EXCEPT AS SPECIALLY CONTEMPLATED BY SECTION 3, IIM shall not MAINTAIN
   CUSTODY OF CLIENT FUNDS OR SECURITIES OR OTHERWISE act as custodian for the
   Account."
4.  AMENDMENT TO SECTION 9 OF THE AGREEMENT. Section 9 of the Agreement is
    hereby amended to read as follows:
   SECTION 9. LIMITATION OF LIABILITY--In rendering services under this
   Agreement, IIM will not be subject to any liability to Client or to any other
   party for any act or omission of IIM except as a result of IIM's negligence,
   misconduct or violation of applicable law. Nothing herein shall in any way
   constitute a waiver or limitation of any rights of any party under applicable
   Federal or State law.
<Page>
5.  AMENDED AGREEMENT. Except as specifically amended by this Amendment, each
    and every term of this Agreement remains in full force and effect.

<Table>
<S>                                     <C>
CLIENT:                                 ING INSURANCE COMPANY OF AMERICA

                                        By: /s/ Paula Cludray-Engelke
                                        ----------------------------------------
                                        Name: Paula Cludray-Engelke
                                        Title: Secretary

IIM:                                    ING INVESTMENT MANAGEMENT LLC

                                        By: /s/ Fred C. Smith
                                        ----------------------------------------
                                        Name: Fred C. Smith
                                        Title: Executive Vice President
</Table>