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 W P 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. Davis, who became a director of NYFIX, Inc. (the "Company") on October 12,
2006, is a partner of WP, and a member and Managing Director of WP LLC. As such,
Mr. Davis 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. Davis disclaims beneficial
ownership of such securities, except to the extent of any indirect pecuniary
interest therein. Mr. Davis 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. Davis, who became a director of the Company on October 12, 2006, is a
partner of WP, and a member and Managing Director of WP LLC. As such, Mr. Davis
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.
Davis disclaims beneficial ownership of the Warrant, except to the extent of any
indirect pecuniary interest therein. Mr. Davis does not directly own the
Warrant.