From The Free Forex Encyclopedia
Standard and Poor’s (S&P) is currently one of the Big Three players in the credit rating industry.
In 1941 Standard Statistics (publisher of sovereign debt and bonds ratings) merged with Henry Varnum Poor, the publisher of "History of the Railroads and Canals of the United States," which is one of the first attempts at compiling financial details of the U.S. railroads.
Today, S&P is not only known for its ratings, it's also closely watched for its ratings on market indices (ex. S&P 500, S&P/Case-Shiller home price index).