<PAGE>
 
                                                                   EXHIBIT 10(M)

                 [Letterhead of First Chicago NBD Corporation]

 

Timothy P. Moen
Executive Vice President
Human Resources



                               November 13, 1997


PERSONAL & CONFIDENTIAL
-----------------------

Mr. Scott P. Marks, Jr.
Vice Chairman
First Chicago NBD Corporation



Dear Scott:

This letter agreement will confirm the terms of your separation from First
Chicago NBD Corporation ("FCNBD") and all of its subsidiaries and affiliates,
including The First National Bank of Chicago ("FNBC") (collectively, "FCN").

Resignation

You have voluntarily elected to resign as Vice Chairman of FCNBD and from all
offices and directorships you hold with FCNBD and all of its subsidiaries and
affiliates, effective at the close of business December 31, 1997 (your
"Resignation Date"), and your resignation, effective on that date, is hereby
accepted. By the close of business on November 13, 1997, you will submit a
letter, substantially in the form attached as Exhibit A, evidencing such
resignation. Until your Resignation Date, you will continue to use your best
efforts to perform the duties of your current position and to assist in the
transition related to your departure.

FCNBD's Obligations

Though you will not perform any services for FCN after your Resignation Date,
subject to the terms of this letter, you will remain on the FNBC payroll at your
current base salary rate and be treated as an active employee for salary
continuation and most employee benefit purposes (including eligibility for
medical, pension and 401(k) plans, life insurance coverage and the employee
stock purchase and executive stock incentive plans) for the period through March
31, 1998. From April 1, 1998 through June 30, 1998, you will remain on the FNBC
payroll in an unpaid leave status, and will have all of the rights and benefits
attendant to that status, including
<PAGE>
 
Mr. Scott P. Marks, Jr.
November 13, 1997
Page 2


continued eligibility under the medical plan. You will not be eligible for short
or long-term disability benefits and you will not earn any additional vacation
days after your Resignation Date, though you will be paid for any accrued,
unused vacation days outstanding as of your Resignation Date. Effective July 1,
1998, you will be removed from the FNBC payroll, and your employment with FCNBD
and all of its affiliates and subsidiaries will terminate for all purposes.

You will be eligible for a 1997 incentive bonus, payable in the first quarter of
1998, determined on a "full and fair" basis, comparable to other FCNBD Vice
Chairmen. You will not receive any additional stock awards under the FCNBD Stock
Performance Plan after your Resignation Date, though you will continue to be
treated as an active employee under that plan for as long as you are on the FNBC
payroll, in paid or unpaid status.

FCNBD will provide you with office space (including telephone), secretarial
support and executive parking privileges for the period from your Resignation
Date through March 31, 1998. Thereafter, office space, secretarial support and
parking will be available to you at the discretion of FCNBD's Chairman.

Notwithstanding anything in this letter to the contrary, in the event of your
death while you are on the FNBC payroll (in paid or unpaid status), your estate
will be paid any remaining salary continuation for the period through March 31,
1998 in a single sum, and your employment will be terminated for all purposes as
of the date of death. Your outstanding stock options, restricted shares and
performance shares as of that date will become vested and payable in accordance
with the plan under which they were granted as if you died while actively
employed.

To the maximum extent provided under FCNBD's by-laws or Certificate of
Incorporation as in effect from time to time, you will be indemnified, defended
and held harmless against judgments, fines, amounts paid in settlement and
reasonable expenses (including attorneys' fees) incurred by you in the defense
of any lawsuit to which you are made a party by reason of the fact that you were
an officer, director or employee of FCNBD or any of its subsidiaries or
affiliates.

FCNBD's obligations hereunder will be null and void if it is discovered that you
have engaged in any intentional wrongful act related to your employment with
FCNBD or any of its affiliates or subsidiaries.

Your Obligations

As a condition precedent to FCNBD's obligations hereunder, you will provide FCN
with the General Release below.

On or before June 30, 1998, you will return to FCNBD all property of FCNBD or
any of its subsidiaries or affiliates which is in your possession including,
without limitation, reports, files,
<PAGE>
 
Mr. Scott P. Marks, Jr.
November 13, 1997
Page 3


memoranda, correspondence, door and file keys, identification cards, credit
cards, computer access codes, customer and client lists, and other property or
materials which you prepared or helped to prepare or to which you had access,
and you will not retain any reproductions thereof. You agree to cooperate with
FCNBD and any of its counsel in connection with any investigation or litigation
relating to any matter in which you were involved during your employment with
FCN.

You agree to hold in a fiduciary capacity for the benefit of FCNBD all secret or
confidential information, knowledge or data relating to FCN and its respective
businesses, which you have obtained during your employment with FCN and which
has not been publicly disclosed (other than by your acts or the acts of your
representatives). You shall not, without the prior written consent of FCNBD or
as may otherwise be required by law or legal process, communicate or divulge any
such information, knowledge or data to anyone other than to FCNBD and those
designated by it. You also agree not make any negative, critical or disparaging
remarks to the press or any other third party concerning FCNBD or any of its
subsidiaries or affiliates or any of their officers or employees. You further
agree not to disclose the terms of this letter agreement to anyone other than
members of your immediate family, your attorney in this matter or your
accountant or your financial advisor or as otherwise required by law, until the
terms have been publicly disclosed. FCNBD agrees not to disclose the terms of
this agreement to anyone other than those with a need to know within FCNBD until
the terms have been publicly disclosed. A violation of the provisions of this
paragraph shall constitute a basis for deferring or withholding any amounts
otherwise payable to you under this letter agreement.

Miscellaneous

From and after the date it is executed, this letter agreement shall supersede
any employment, severance or change of control agreement between you and FCNBD
or any of its subsidiaries or affiliates.

We hereby advise you that you have the right to consult with an attorney before
signing this agreement. FCNBD understands and you hereby represent that you have
carefully read and fully understand all of the provisions of this agreement and
you are voluntarily entering into this agreement. You have a period of 21 days
to consider this agreement. If you elect to enter into this agreement prior to
the expiration of 21 days, you hereby acknowledge that you do so knowingly and
willingly. You may revoke this letter agreement at any time within seven days
following the date you sign below, and its terms shall not be effective or
enforceable until the revocation period has expired.
<PAGE>
 
Mr. Scott P. Marks, Jr.
November 13, 1997
Page 4


If you are in agreement with the foregoing terms, please sign the attached copy
of this letter and return it to me. If you have any questions, please feel free
to call me.

                                                            Sincerely,

                                                            /s/ Timothy P. Moen



     Enclosure

******************************************************************************
                                GENERAL RELEASE

I agree with the foregoing terms of my separation from FCN and acknowledge that
the consideration furnished above is in excess of the benefits to which I would
otherwise have been entitled, given my voluntary resignation. In consideration
of FCNBD's agreement as set forth above, I hereby release, acquit and forever
discharge First Chicago NBD Corporation, FNBC and all of their affiliated,
predecessor and successor entities and their respective officers, employees,
directors and assigns from any and all claims, actions or causes of action in
any way related to my employment with FCN or the termination thereof, whether
arising from tort, statute or contract, including but not limited to claims
arising under the Age Discrimination in Employment Act of 1967, as amended, the
Older Workers Benefit Protection Act of 1990, Title VII of the Civil Rights Act
of 1964, as amended, the Civil Rights Act of 1991, the Illinois Human Rights
Act, The Americans with Disabilities Act of 1990, the City of Chicago Human
Rights Ordinance, and the Cook County Human Rights Ordinance, it being my
intention and the intention of FCNBD to make this release as broad and as
general as the law permits. I fully understand and voluntarily agree to this
release.



/s/ Scott P. Marks, Jr.      November 14, 1997
-----------------------      -----------------
Scott P. Marks, Jr.          Date
<PAGE>
 
                                                                       EXHIBIT A



Board of Directors
First Chicago NBD Corporation


To All Directors:

I hereby resign, effective December 31, 1997, from all offices, directorships
and positions on committees I hold with First Chicago NBD Corporation and all of
its affiliated and subsidiary banks and corporations.



                                                            Very truly yours,



                                                            Scott P. Marks, Jr.



Dated: November 13, 1997