ISE Plans Public Secondary Offering

The International Securities Exchange, Inc. (NYSE: ISE)
said today that, at some time following the public release of its
results for the third quarter of 2005, it plans to file with the
Securities and Exchange Commission a registration statement for an
offering of shares of its Class A common stock by certain stockholders
and management in an underwritten secondary public offering. ISE will
not receive any proceeds from the sale of the shares.
   The offering is currently expected to commence during the fourth
quarter of 2005 or first quarter of 2006, subject to the SEC declaring
the registration statement effective and the receipt of all necessary
approvals.
   This announcement shall not constitute an offer to sell or the
solicitation of an offer to buy any securities described herein, nor
shall there be any sale of these securities in any state or
jurisdiction in which the offer, solicitation or sale would be
unlawful. This announcement is being issued pursuant to and in
accordance with Rule 135 under the Securities Act of 1933.

   ISE Background

   The International Securities Exchange was founded on the principle
that technology fosters and infuses new efficiencies and operational
innovations into securities trading. After developing an innovative
market structure that integrated auction market principles into an
advanced screen-based trading system, ISE launched the first fully
electronic US options exchange in May 2000. ISE continually enhances
its trading systems to provide investors with the best marketplace to
execute their options orders.
   For more information about ISE, its products and its technology,
visit www.iseoptions.com.

   This press release contains "forward looking statements." These
statements relate to future events or our future financial
performance, and involve known and unknown risks, uncertainties and
other factors that may cause our actual results, levels of activity,
performance or achievements, to be materially different from those
contemplated by the forward looking statements. We undertake no
ongoing obligation, other than that imposed by law, to update these
statements. Factors that could affect our results, levels of activity,
performance or achievements and cause them to materially differ from
those contained in the forward looking statements can be found in our
filings with the Securities and Exchange Commission, including our
registration statement on Form S-1, current reports on Form 8-K and
quarterly reports on Form 10-Q.