<PAGE>

                                POWER OF ATTORNEY

     Each of the undersigned, as a member of the Board of Directors (the
"Board"), or as an officer, or as a member of a committee of the Board, or in
two or more of such capacities, of Instinet Group Incorporated, a Delaware
corporation ("Instinet"), hereby constitutes and appoints MARK NIENSTEDT and
PAUL A. MEROLLA, and each of them singly, his or her true and lawful
attorney-in-fact and agent, with full power of substitution and resubstitution,
to act, for him or her and in his or her name, place and stead and on his or her
behalf, in any and all capacities, to sign Instinet's Annual Report on Form 10-K
for the fiscal year ended December 31, 2001, and any and all amendments to such
Form 10-K and other documents relating thereto, and to file on behalf of
Instinet such Annual Report on Form 10-K and any such amendments, with all
exhibits thereto, and any and all other information and documents in connection
therewith, with the Securities and Exchange Commission (the "SEC"), hereby
granting unto said attorneys-in-fact and agents, and each one of them, full
power and authority to do and perform any and all acts and things requisite to
enable Instinet to comply with the Securities Exchange Act of 1934 and any rules
and regulations and requirements of the SEC in respect thereof in connection
with the filing of Instinet's Annual Report on Form 10-K as fully to all intents
and purposes as he or she might or could do in person as a director of Instinet,
hereby ratifying and confirming all that said attorneys-in-fact and agents, or
any one of them, may lawfully do or cause to be done by virtue hereof.

<TABLE>
<CAPTION>
          SIGNATURE                                                       TITLE
<S>                                                     <C>
/s/    Douglas M. Atkin                                 President, Chief Executive Officer and Director
---------------------------------------
Name:  Douglas M. Atkin

/s/    Mark Nienstedt                                   Executive Vice President, Chief Financial Officer and
---------------------------------------                 Director
Name:  Mark Nienstedt

/s/    Andre F.H. Villeneuve                            Director and Chairman of the Board of Directors
---------------------------------------
Name:  Andre F.H. Villeneuve

/s/    Peter J. Job                                     Director
---------------------------------------
Name:  Peter J. Job

/s/    Thomas H. Glocer                                 Director
---------------------------------------
Name:  Thomas H. Glocer

/s/    Ian Strachan                                     Director
---------------------------------------
Name:  Ian Strachan

/s/    David Grigson                                    Director
---------------------------------------
Name:  David Grigson
</TABLE>
<PAGE>
<TABLE>
<S>                                                     <C>
/s/    John C. Bogle                                    Director
---------------------------------------
Name:  John C. Bogle

/s/    John Kasich                                      Director
---------------------------------------
Name:  John Kasich

/s/    Kay Koplovitz                                    Director
---------------------------------------
Name:  Kay Koplovitz
</TABLE>


Dated: March 21, 2002


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