Spider

SPDR. Shares of a security designed to track the value of the S&P 500. Spiders trade on the American Stock Exchange under the symbol SPY. One SPDR unit is valued at approximately one-tenth of the value of the S&P 500. Dividends are distributed quarterly, and are based on the accumulated stock dividends held in trust, less any expenses of the trust. also called Standard & Poor's Depositary Receipt.