Instinet Group Announces June 2004 Transaction Information

Instinet Group Incorporated (NASDAQ: INGP) today announced June 2004 transaction data for its two major business segments: Instinet, the Unconflicted Institutional Broker and INET, the Electronic Marketplace.

In June 2004, Instinet's total average daily U.S. equity share volume was 88 million shares, which represents a 2.5% share of the U.S. equity market. This compares to 104 million shares, or 2.7% of the U.S. equity market, in May 2004, and 103 million shares, or 2.5% of the U.S. equity market, in June 2003.

In June 2004, INET's total matched average daily U.S. equity share volume was 451 million shares, or 13.0% of the U.S. equity market. This volume consisted of 392 million shares of NASDAQ-listed stocks, or a 24.5% share of the NASDAQ-listed market, and 59 million shares of U.S. exchange-listed stocks, or 3.1% of the U.S. exchange-listed market.

This compares to INET's total matched average daily share volume of 507 million in May 2004, or 13.4% of the U.S. equity market, consisting of 426 million shares of NASDAQ-listed stocks, or a 25.6% share of the NASDAQ-listed market, and 81 million shares of U.S. exchange-listed stocks, or 3.8% of the U.S. exchange-listed market.

In June 2003, INET's total matched average daily share volume was 549 million shares, or 13.4% of the U.S equity market, consisting of 498 million shares of NASDAQ-listed stocks, or a 24.5% share of the NASDAQ-listed market, and 52 million shares of U.S. exchange-listed stocks, or 2.5% of the U.S. exchange-listed market.

Instinet Group reports additional monthly operating data on its website at www.instinetgroup.com under the heading "Investor Relations - Instinet Trading Activity."

	June 2004	May 2004	June 2003 (3)
# of Trade Days	21	20	21
Instinet (1)
Total U.S. equity average daily volume (million shares)	88	104	103
Share of total U.S. equity market	2.5%	2.7%	2.5%
INET - Matched Average Daily Volume (2)
Nasdaq-listed equity share volume (million shares)	392	426	498
Share of total Nasdaq market	24.5%	25.6%	24.5%
U.S. exchange-listed share volume (million shares)	59	81	52
Share of total U.S. exchange-listed market	3.1%	3.8%	2.5%
Total U.S. equity share volume (million shares)	451	507	549
Share of total U.S. equity market	13.0%	13.4%	13.4%

Monthly totals may not reflect weekly data, which are preliminary. The number of trading days in each period takes account of U.S. market holidays and any other U.S. market closings.

1. For a description of how we calculate Instinet's transaction volumes, see "Management's Discussion and Analysis of Financial Condition and Results of Operations - Calculation of Volume - Instinet, the Institutional Broker" in our Form 10-Q for the fiscal quarter ended March 31, 2004.
2. For a description of how we calculate INET's transaction volumes, see "Management's Discussion and Analysis of Financial Condition and Results of Operations - Calculation of Volume - INET, the Electronic Marketplace" in our Form 10-Q for the fiscal quarter ended March 31, 2004.
3. Represents Inet ATS, Inc. volume, including volume from ProTrader Securities L.P. beginning the week ended 10/5/01 through 7/22/03.

Instinet has experienced significant seasonality in its business, and period-to-period comparisons of operating results are not necessarily meaningful, nor are the results for any period necessarily indicative of results for any future period.