Boston, May 24, 2005 - State Street Global Markets, the investment research and trading arm of State Street Corporation (NYSE:STT), released today the results of the State Street Investor Confidence Index^SM for May 2005.

According to the May index, investor confidence decreased by 5.5 points from April's revised reading of 89.4.

Developed by Harvard University professor Ken Froot and Paul O'Connell of State Street Associates, the research unit of State Street Global Markets, the index measures investor confidence on a quantitative basis, analyzing actual buying and selling patterns of institutional investors. The index is based on the financial theory that assigns precise meaning to changes in investor risk sentiment, or the willingness of investors to hold proportionally more or less of their portfolio in higher-risk investments.

"During May the confidence of institutional investors in equity markets fell substantially," commented O'Connell. "This was particularly the case for U.S. investors, who have been reducing their exposures to risky assets across their portfolios. The risk appetite of Asian institutional investors, by contrast, improved somewhat."

"These negative effects were strongest in the first two weeks of May," added Froot. "This is not too surprising, given the developments in the global debt markets. We are seeing investors moving strongly toward 'safer' assets, such as U.S. Treasuries, and away from corporate debt, where spreads have widened. Ratings changes, even after changes in fundamentals, appear to have important impacts on markets and prices."

Since its launch in September of 2003, the State Street Investor Confidence Index^SM has become a key economic indicator for asset owners, investment managers and central banks. As the only index providing a quantitative measure tracking the common buying patterns of institutional investors around the world, the State Street Investor Confidence Index^SM offers a unique look into the investment behavior and decisions of thousands of professional investors and their investment decisions.

About State Street Global Markets
State Street Global Markets provides specialized investment research and trading in foreign exchange, equities, fixed income and derivatives. Its goal is to enhance and preserve portfolio values for asset managers and asset owners. From its unique position at the crossroads of the global markets, it creates and unlocks value for its clients with original flow-based research, innovative portfolio strategies, trade process optimization, and global connectivity across multiple asset classes and markets.

About State Street Associates
Founded in 1999 in Cambridge, Mass., State Street Associates develops portfolio and flow research, currency management, asset allocation services and designs strategy tools to support the needs of global portfolio managers.

About the State Street Investor Confidence Index^SM
The index is released globally at 10 a.m. Eastern time in Boston on the second to last Tuesday of each month. More information on the State Street Investor Confidence Index, and the calendar of release dates, is available at http://www.statestreet.com/investorconfidenceindex. The previous month's calculations for the index are revised to account for trading activity through the end of the reporting period.

About State Street
State Street Corporation (NYSE: STT) is the world's leading specialist in providing institutional investors with investment servicing, investment management and investment research and trading. With $9.5 trillion in assets under custody and $1.4 trillion in assets under management, State Street operates in 25 countries and more than 100 markets worldwide. For more information, visit State Street's Web site at www.statestreet.com.

This news announcement contains forward-looking statements as defined by United States securities laws, including statements about the financial outlook and business environment. Those statements are based on current expectations and involve a number of risks and uncertainties, including those related to the pace at which State Street adds new clients or at which existing clients use additional services, the value of global and regional financial markets, the pace of cross-border investment activity, changes in interest rates, the pace of worldwide economic growth and rates of inflation, the extent of volatility in currency markets, consolidations among clients and competitors, State Street's business mix, the dynamics of markets State Street serves, and State Street's success at integrating and converting acquisitions into its business. Other important factors that could cause actual results to differ materially from those indicated by any forward-looking statements are set forth in State Street's 2004 annual report and subsequent SEC filings. State Street encourages investors to read the corporation's annual report, particularly the section on factors that may affect financial results, and its subsequent SEC filings for additional information with respect to any forward-looking statements and prior to making any investment decision. The forward-looking statements contained in this press release speak only as of the date hereof, May 24, 2005, and the company will not undertake efforts to revise those forward-looking statements to reflect events after this date.