AGREEMENT

                                                                   
EXHIBIT 10.33

                                    
AGREEMENT

            
Reference is hereby made to that certain Purchase
  
Agreement,
  
dated

as of December 30, 2004 (the
  
"Purchase
  
Agreement"),
  
by and among NYFIX,
  
Inc.

("NYFIX")
  
and
  
Whitebox
  
Convertible
  
Arbitrage
  
Partners
  
L.P.
   
("Whitebox"),

pursuant to which Whitebox purchased a $7,500,000 convertible
promissory note of

NYFIX (the "Original Note"). All capitalized terms used herein but
not otherwise

defined
  
herein
  
shall
  
have
  
the
  
meanings
  
ascribed
  
to them
  
in the
  
Purchase

Agreement.

            
Pursuant to Section 2.2 of the Purchase Agreement,
  
Whitebox had the

option to elect within 90 days after the Closing Date (the
"Election Period") to

purchase up to an additional $2,500,000
  
convertible promissory note on the same

terms and conditions as the Original Note.

            
The parties hereto