NEW YORK, March 29 (Reuters) - Standard & Poor's on Monday said it will add Affiliated Computer Services Inc. to its flagship 500 stock index and drop Travelers Property Casualty Corp. from the index after the close of trading on April 1.
Affiliated, which is based in Dallas, handles billing and other operations for companies and governments. Travelers, which is based in Hartford, Connecticut, is being bought by St. Paul Cos. to create the second-largest U.S. commercial property insurer.
Changes in the S&P 500 index can cause added volatility or trading volume in shares of companies being added or removed. Many portfolio managers try to track the index and are required by charter to buy or sell stocks that enter or exit the index.
S&P also said Thor Industries Inc. , a Jackson Center, Ohio-based seller of recreational vehicles, will replace Affiliated in its MidCap 400 index.