CHICAGO, May 11 /PRNewswire-FirstCall/ -- Archipelago Holdings, Inc. (PCX: AX) today announced its April 2005 market transaction volume data for the Archipelago Exchange (ArcaEx(R)). Specifically, in NYSE- listed equity securities, ArcaEx's total trading market share was 3.2% in April 2005, up from 1.7% in April 2004 and up from 2.7% in March 2005.

In AMEX-listed equity securities, ArcaEx's total trading market share was 29.0% in April 2005, up from 20.1% in April 2004 and up from 26.1% in March 2005. ArcaEx's ETF total monthly share volume showed continued year-over- year growth with 2,213.0 (millions of shares) having traded in April 2005 compared to 1,267.4 (millions of shares) traded in April 2004 and up from 1,899.3 (millions of shares) in March 2005.

In Nasdaq-listed equity securities, ArcaEx's total trading market share was 23.6% in April 2005 down from 25.7% in April 2004 and was up from 22.5% in March 2005.

    ArcaEx Transaction Volume Data

                                               April       March       April

                                                2005        2005       2004

    Total monthly volume of Nasdaq-listed

     equity securities (millions of shares)  38,991.8    41,076.8   40,967.7

    ArcaEx monthly volume of Nasdaq-listed

     equity securities (millions of

     shares)(1)                               9,218.1     9,261.4   10,517.7

    ArcaEx share of total monthly volume

     of Nasdaq-listed  equity

     securities(%)(2)                            23.6%       22.5%      25.7%

    Total monthly volume of NYSE-listed      44,543.4    46,848.2   40,216.1

     equity securities (millions of shares)

    ArcaEx monthly volume of NYSE-listed

     equity securities (millions of

     shares)(1)                               1,445.5     1,274.8      686.2

    ArcaEx share of total monthly volume

     of NYSE-listed equity securities

     (%)(2)                                       3.2%       2.7%       1.7%

    Total  monthly volume of AMEX-listed

     equity securities (millions of shares)   6,159.7     5,899.4    6,859.4

    ArcaEx monthly volume of AMEX-listed

     equity  securities (millions of

     shares) (1)                              1,787.2     1,539.9    1,377.5

    ArcaEx share of total monthly volume

     of AMEX-listed equity

     securities (%)(2)                           29.0%       26.1%      20.1%

    ArcaEx ETF total monthly share volume

     (millions of shares)(1)                  2,213.0      1899.3    1,267.4

    ArcaEx monthly customer order volume

     matched internally (%)(3)                   88.9%       88.1%      85.8%

    ArcaEx monthly customer order volume

     routed out  (%)(3)                          11.1%       11.9%      14.2%

    Number of trading days in period               21          22         21





                        ArcaEx Most Active April 2005



                       Symbol            Share Volume      Market Share

    Nasdaq-100 Index(R)      (QQQQ)       591,910,446         25.1%

    SPDR(R)                  (SPY)        436,769,540         26.2%

    Microsoft(R)             (MSFT)       399,599,107         26.1%

    Intel(R)                 (INTC)       352,674,503         25.6%

    Semiconductor Holdrs(sm) (SMH)        301,471,700         51.1%

    Cisco Systems(R)         (CSCO)       253,339,100         22.3%

    Oracle(R)                (ORCL)       201,250,854         23.3%

    Sun(R) Microsystems      (SUNW)       198,271,802         23.6%

    Energy Select SPDR(R)    (XLE)        170,323,854         45.6%

    Siebel Systems           (SEBL)       164,390,102         27.0%

Additional information on ArcaEx daily, weekly and monthly trading transaction volumes is publicly available in real time through the ArcaVision website accessible via http://www.archipelago.com. Additional data and enhanced functionality can be obtained through a free subscription to ArcaVision. Investors and ArcaEx clients can subscribe to ArcaVision at http://www.arca-vision.com.

    (1) For purposes of calculating monthly transaction volume on ArcaEx, we

        include all shares that are "handled" on ArcaEx for the month.

        Handled shares include both shares that are bought and sold during the

        month within our internal liquidity pool and shares that are routed to

        external market centers for execution.



    (2) ArcaEx monthly market share is calculated based on the number of

        shares handled on the ArcaEx system during the month as a percentage

        of total monthly volume. Total monthly volume is based on the number

        of shares of equity securities traded during the month on Nasdaq, AMEX

        or the NYSE, including, if applicable, exchange-traded funds, as

        reported in the consolidated tape.  The "consolidated tape" provides

        last sale price and volume of equity securities transactions to the

        public.



    (3) In computing the percentage of monthly client order volume matched

        internally and the monthly percentage of customer order volume routed

        out, we calculate the percentage based on the volume of individual

        customer orders, not the volume of matched trades (i.e., only counting

        one side of a matched transaction). For example, we calculate two

        customer orders matched internally on our system as two customer

        orders matched internally, and we include the volume of both the buy

        order and the sell order in computing our percentages of monthly

        customer order volume matched internally and routed out. We calculate

        one customer order routed to an external market center (which will be

        matched with an order at that other market center) as one outbound

        trade or one customer order. We calculate one customer order routed to

        us from an external market center and matched with an order on our

        system as one inbound trade or one customer order.

Archipelago Holdings (PCX: AX) operates The Archipelago Exchange(R) (ArcaEx(R)) the first totally open all- electronic stock exchange in the United States. ArcaEx trades all Nasdaq-listed equity securities and exchange listed equity securities, including those listed on the New York Stock Exchange(R), American Stock Exchange(R), and Pacific Exchange(R). In addition to offering core execution services, ArcaEx provides corporate clients with listing services and innovative data products. In 2004, Archipelago launched ArcaVision to provide corporate and trading clients with more transparent market data, analytical tools and access to market-wide and ArcaEx specific trading information. Archipelago Holdings completed its initial public offering in August 2004. For more information please visit http://www.archipelago.com.

ArcaEx's, past transaction performance is not necessarily indicative of its future results. Periodically, ArcaEX's transaction performance will experience fluctuations due to unforeseen factors effecting trading activity, including seasonality, general economic, political and market conditions, unforeseen market closures or other disruptions in trading. A description of the factors that may influence ArcaEx's volume of securities transactions are identified in Archipelago's Prospectus, dated August 12, 2004.

Certain statements in this press release may contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These statements are based on Archipelago's current expectations and involve risks and uncertainties that could cause Archipelago's actual results to differ materially from those set forth in the statements. There can be no assurance that such expectations will prove to be correct. Factors that could cause Archipelago's results to differ materially from current expectations include: general economic and business conditions, industry trends, competitive conditions, regulatory developments as well as other risks or factors identified in the Company's filings with the Securities Exchange Commission, including its Report on Form 10-K for the fiscal year ending December 31, 2004 which is available on the Company's website at http://www.archipelago.com. You should not place undue reliance on forward- looking statements, which speak only as of the date of this press release. Except for any obligation to disclose material information under the Federal securities laws, Archipelago undertakes no obligation to release publicly any revisions to any forward-looking statements to reflect events or circumstances after the date of this press release.

SOURCE Archipelago Holdings, Inc.
05/11/2005
CONTACT: Margaret Nagle - Press +1-312-442-7083, or Patrick Murphy - Investor Relations, +1-312-442-7005, both for Archipelago
(AX)