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The S&P 500 stock market index is introduced, replacing the S&P 90.
Related Wikipedia articles
S&P 500
American stock market index
The Standard and Poor's 500, or simply the S&P 500, is a stock market index tracking the stock performance of 500 leading companies listed on stock exchanges in the United States. It is one of the most commonly followed equity indices and includes approximately 80% of the total…Source: Wikipedia (CC BY-SA)
Stock market index
Financial metric which investors use to determine market performance
In finance, a stock index, or stock market index, is an index that measures the performance of a stock market, or of a subset of a stock market. It helps investors compare current stock price levels with past prices to calculate market performance.Source: Wikipedia (CC BY-SA)