EXHIBIT 24

                            LIMITED POWER OF ATTORNEY FOR
                            SECTION 16 REPORTING PURPOSES

		Know all by these presents, that the undersigned hereby makes,
constitutes and appoints each of Charles R. Hood, Antonio L. DeLise and Ori
Solomon, acting individually, as the undersigned's true and lawful attorney-
in-fact, with full power and authority as hereinafter described on behalf of
and in the name, place and stead of the undersigned to:

        (1) execute for, and on behalf of, the undersigned, in the undersigned's
capacity as an officer and/or director of MarketAxess Holdings Inc. (the
"Company"), Forms 3, 4, and 5 in accordance with Section 16(a) of the Securities
Exchange Act of 1934 and the rules and regulations promulgated thereunder, as
amended from time to time (the "Exchange Act");

        (2) seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information on transactions in the Company's securities
from any third party, including brokers, employee benefit plan administrators
and trustees, and the undersigned hereby authorizes any such person to release
any such information to any attorney-in-fact and further approves and ratifies
any such release of information;

        (3) do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to prepare, complete and execute
any such Form 3, 4 or 5, and any amendments thereto, or other required report
and timely file such Forms or reports with the United States Securities and
Exchange Commission, the Nasdaq Stock Market and any stock exchange or similar
authority as considered necessary or advisable under Section 16(a) of the
Exchange Act; and

        (4) take any other action solely in connection with the matters
specifically enumerated above 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 such attorney-in-fact's sole discretion.

        The undersigned hereby gives and grants to each such attorney-in-fact
full power and authority to do and perform any and every act and thing
whatsoever requisite, necessary, or proper to be done in the exercise of any of
the rights and powers herein granted, as fully to all intents and purposes as
the undersigned 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 such attorney-in-fact's 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 hereby acknowledges that (a) the foregoing attorneys-in-
fact are serving in such capacity at the request of the undersigned; (b) this
Limited Power of Attorney authorizes, but does not require, each such attorney-
in-fact to act in their discretion on information provided to such attorney-in-
fact without independent verification of such information; (c) any documents
prepared and/or executed by any attorney-in-fact on behalf of the undersigned
pursuant to this Limited Power of Attorney shall be in such form and shall
contain such information and disclosure as such attorney-in-fact, in his or her
sole discretion, deems necessary or advisable; (d) neither the Company nor any
attorney-in-fact assumes (i) any liability for the undersigned's responsibility
to comply with the requirements of the Exchange Act, (ii) any liability of the
undersigned for any failure to comply with such requirements, or (iii) any
obligation or liability of the undersigned for profit disgorgement under
Section 16(b) of the Exchange Act; and (e) this Limited Power of Attorney does
not relieve the undersigned from responsibility for compliance with the
undersigned's obligations under the Exchange Act, including, without limitation,
the reporting requirements under Section 16 of the Exchange Act.

        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 as to any attorney-in-fact by the undersigned in
a signed writing delivered to such attorney-in-fact.  In affixing his signature
to this Power of Attorney, the undersigned hereby revokes any and all previously
executed Powers of Attorney for the same or similar purposes.

        IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 15th day of March, 2012.


						              /s/ James J. Sullivan	           
						              James J. Sullivan