Exhibit 99.1

                            Explanation of Responses:

(1) The Series B Voting Convertible Preferred Stock ("Preferred Stock") is
convertible, in whole or in part, at any time and from time to time at the
holder's election. At any time after April 12, 2008, the Preferred Stock is
convertible at the option of the Issuer, in whole or in part, if the price
per share of the Issuer's common stock, par value $0.001 per share ("Common
Stock") reaches certain levels. The conversion rights do not expire.

(2) Each share of Preferred Stock is initially convertible into 10 shares of
Common Stock at an initial conversion price of $5.00 per share, subject to
certain adjustments in accordance with the terms of the Preferred Stock.

(3) Warburg Pincus Private Equity IX, L.P., a Delaware limited partnership
("WP IX"), is the direct record owner of 1,500,000 shares of Preferred Stock,
which is convertible into 15,000,000 shares of Common Stock. The sole general
partner of WP IX is Warburg Pincus IX, LLC, a New York limited liability
company ("WP IX LLC"); Warburg Pincus Partners, LLC, a New York limited
liability company ("WPP LLC"), is the sole member of WP IX LLC; Warburg
Pincus & Co., a New York general partnership ("WP"), is the managing member
of WPP LLC; Warburg Pincus LLC, a New York limited liability company ("WP
LLC"), manages WP IX; and Charles R. Kaye and Joseph P. Landy are each
Managing General Partners of WP and Co-Presidents and Managing Members of WP
LLC. By reason of the provisions of Rule 16a-1 of the Securities Exchange Act
of 1934, as amended (the "Act"), WP, WP LLC, WPP LLC, WP IX LLC, Mr. Kaye and
Mr. Landy may be deemed to be the beneficial owners of any securities that
may be deemed to be beneficially owned by WP IX. Each of WP, WP LLC, WPP LLC,
WP IX LLC, Mr. Kaye and Mr. Landy disclaim beneficial ownership of all shares
of the Preferred Stock beneficially owned by WP IX, except to the extent of
any indirect pecuniary interest therein.

Mr. Janeway, who became a director of NYFIX, Inc. (the "Company") on October
12, 2006, is a partner of WP, and a member and Vice Chairman of WP LLC. As
such, Mr. Janeway may be deemed to have an indirect pecuniary interest
(within the meaning of Rule 16a-1 of the Act) in an indeterminate portion of
the securities reported as beneficially owned by WP IX. Mr. Janeway disclaims
beneficial ownership of such securities to the extent of any indirect
pecuniary interest therein. Mr. Janeway does not directly own any shares of
Preferred Stock.

(4) The Warrant to Purchase Common Stock (the "Warrant") is convertible at
any time, in whole or in part, at the holder's option until 5:00 p.m. Eastern
Time on October 12, 2016, at which point the Warrant expires.

(5) The exercise price of the Warrant is initially equal to $7.50 per share
of Common Stock, subject to certain adjustments in accordance with the terms
of the Warrant.

(6) WP IX is the direct record owner of the Warrant, which is convertible
into 2,250,000 shares of Common Stock. The sole general partner of WP IX is
WP IX LLC; WPP LLC is the sole member of WP IX LLC; WP is the managing member
of WPP LLC; WP LLC manages WP IX; and Charles R. Kaye and Joseph P. Landy are
each Managing General Partners of WP and Co-Presidents and Managing Members
of WP LLC. By reason of the provisions of Rule 16a-1 of the Act, WP, WP LLC,
WPP LLC, WP IX LLC, Mr. Kaye and Mr. Landy may be deemed to be the beneficial
owners of any securities that may be deemed to be beneficially owned by WP
IX. Each of WP, WP LLC, WPP LLC, WP IX LLC, Mr. Kaye and Mr. Landy disclaim
beneficial ownership of the Warrant beneficially owned by WP IX, except to
the extent of any indirect pecuniary interest therein.

Mr. Janeway, who became a director of the Company on October 12, 2006, is a
partner of WP, and a member and Vice Chairman of WP LLC. As such, Mr. Janeway
may be deemed to have an indirect pecuniary interest (within the meaning of
Rule 16a-1 of the Act) in the Warrant reported as beneficially owned by WP
IX. Mr. Janeway disclaims beneficial ownership of the Warrant to the extent
of any indirect pecuniary interest therein. Mr. Janeway does not directly own
the Warrant.