ISE Reports Monthly Volume for December 2005; Average Daily Volume Increases 22% for the Month; Full Year 2005 Volume Increases

The International Securities Exchange, Inc. (NYSE:ISE)
today reported average daily trading volume for equity and index
options contracts for December 2005. Average daily trading volume
increased 22.3% to 1.8 million contracts per day as compared to 1.5
million contracts per day during the same period in 2004. Total equity
and index options volume for the month increased 16.7% to 37.7 million
contracts from 32.3 million contracts in the same year-ago period.
   For the year 2005, average daily trading volume of equity and
index options increased 24.3% to a record 1.8 million contracts traded
as compared to 1.4 million contracts traded in 2004. Total equity and
index volume for 2005 increased 24.3% to 448.7 million contracts from
360.9 million contracts in 2004.

-0-
*T
Equity and Index Options Volume Statistics

                    Current Month                Year-to-Date
(000s)        Dec-05   Dec-04   % Change   Dec-05    Dec-04   % Change
----------------------------------------------------------------------
ISE Average
 Daily
 Volume       1,796.7   1,469.2    22.3%   1,780.5    1,432.0   24.3%
ISE Total
 Volume      37,730.8  32,321.9    16.7% 448,695.7  360,852.5   24.3%
Industry
 Average
 Daily
 Volume       6,539.7   4,777.6    36.9%   5,968.9    4,689.7   27.3%
Market Share    27.5%     30.8%    (3.3)     29.8%      30.5%   (0.7) 
                                    pts                          pts
ISE Market                                              
 Share:
 Customer       30.7%     31.5%    (0.8)     30.3%      27.5%    2.8
                                    pts                          pts
ISE Market                                             
 Share:
 Firm           18.7%     19.9%    (1.2)     22.0%      20.1%    1.9
                                    pts                          pts
ISE Market                                           
 Share:
 Market
 Maker          27.4%     32.6%    (5.2)     31.5%      36.1%   (4.6)
                                    pts                          pts
----------------------------------------------------------------------


Equity Options Volume Statistics

                    Current Month                Year-to-Date
(000s)        Dec-05   Dec-04   % Change   Dec-05    Dec-04   % Change
----------------------------------------------------------------------
ISE Average
 Daily
 Volume       1,775.2   1,468.9    20.9%   1,762.8    1,431.6   23.1%
ISE Total
 Volume      37,278.8  32,315.0    15.4% 444,231.1  360,769.2   23.1%
Industry
 Average
 Daily
 Volume       5,998.1   4,375.0    37.1%   5,432.7    4,300.2   26.3%
Market Share    29.6%     33.6%    (4.0)     32.5%      33.3%   (0.8) 
                                    pts                          pts
ISE Market                                             
 Share:
 Customer       33.1%     33.7%    (0.6)     32.7%      29.4%    3.3
                                    pts                          pts
ISE Market                                              
 Share: Firm    20.8%     23.0%    (2.2)     24.7%      22.5%    2.4
                                    pts                          pts
ISE Market                                           
 Share:
 Market Maker   29.3%     35.9%    (6.6)     34.3%      39.7%   (5.4)
                                    pts                          pts 
----------------------------------------------------------------------


Index Options Volume Statistics

                    Current Month                Year-to-Date
(000s)        Dec-05   Dec-04   % Change   Dec-05    Dec-04   % Change
----------------------------------------------------------------------
ISE Average
 Daily 
 Volume          21.5       0.3     N/M       17.7        0.3    N/M
ISE Total
 Volume         452.0       6.9     N/M    4,464.6       83.4    N/M
Industry
 Average
 Daily Volume   541.6     402.7    34.5%     536.1      389.5   37.6%
Market Share     4.0%      0.1%     3.9       3.3%       0.1%    3.2 
                                    pts                          pts
----------------------------------------------------------------------
*T

   Increasingly in 2005, and particularly in December, we witnessed
an increase in trading activity among options market makers on the
Philadelphia Stock Exchange and Pacific Exchange to profit at the
expense of investors who fail to exercise their call options
immediately prior to a stock going ex-dividend. The trades are
transacted in very large quantities in "in-the-money" call options on
the day before the ex-date and occur on exchanges that reduce their
transaction fees to attract these trades. In December, if the volume
from the largest dividend trades were excluded from the monthly data,
ISE's market share of equity options would increase from 29.6% to
32.1%.
   "We continue to focus our attention on absolute volume growth
driven by Customer and Firm trading activity," said David Krell, ISE's
President and Chief Executive Officer. "Ultimately, the success of an
exchange must be based on its acceptance by these two constituencies.
I am pleased to note that ISE remains the number one venue for
Customer and Firm combined trading activity in equity options."

   Monthly Highlights

   --  ISE was the largest U.S. equity options exchange in December.

   --  ISE was the largest U.S. equity options exchange in 2005.

   --  On December 8, 2005 ISE announced the pricing of its secondary
        offering of Class A common stock at $30.00 per share. The
        offering consisted of 8,000,000 shares of Class A common
        stock, all of which were sold by existing stockholders.

   --  ISE traded more volume in 566 of 837 issues in its listings
        than any other options exchange.

   ISE Background

   The International Securities Exchange, the world's largest equity
options 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, as amended.