POWER OF ATTORNEY

For Executing Forms 3, 4 and 5 Pursuant to Section 16(a) of the
Securities Exchange Act


       Know all by these presents, that the undersigned hereby
constitutes and appoints each of Margaret Austin Wright and
Jenelle Chalmers signing singly, his/her true and lawful
attorney in fact to:

(1) execute for and on behalf of the undersigned Forms 3, 4
and 5 and amendments thereto in accordance with Section 16(a)
of the Securities Exchange Act of 1934 and the rules thereunder;

(2) do and perform any and all acts for and on behalf of
the undersigned which may be necessary or desirable to
complete the execution of any such Form 3, 4 and 5 and
the timely filing of such form with the United States
Securities and Exchange Commission and any other authority; and

(3) take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of such attorney in fact,
may be of benefit to, in the best interest of, or legally
required by, the undersigned, it being understood that the
documents executed by such attorney in fact on behalf of the
undersigned pursuant to this Power of Attorney shall be in
such form and shall contain such terms and conditions as
such attorney in fact may approve in his/her discretion.

       The undersigned hereby grants to each such attorney in fact
full power and authority to do and perform all and every act and
thing whatsoever requisite, necessary and proper to be done in
the exercise of any of the rights and powers herein granted, as
fully to all intents and purposes as such attorney in fact might
or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming
all that such attorney in fact, or his/her substitute or
substitutes, shall lawfully do or cause to be done by virtue
of this power of attorney and the rights and powers herein
granted. The undersigned acknowledges that the foregoing
attorney in fact, in serving in such capacity at the request
of the undersigned, are not assuming any of the undersigned's
responsibilities to comply with Section 16 of the Securities
Exchange Act of 1934.

       This Power of Attorney shall remain in full force and
effect until the undersigned is no longer required to file
Forms, 3, 4, and 5 with respect to the undersigned's holdings
of and transactions in securities issued by the Company, unless
earlier revoked by the undersigned in a signed writing delivered
to the foregoing attorneys in fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of this 21 day of June 2021.



Signature:


Print Name: Larry Gerdes