Over the years there has been a growing interest in the over-the-counter (OTC) trading of exchange-listed securities (known as the third market). Although the third market has flourished and its advantages have been expounded, it has not been possible to compare accurately the third market with organized exchanges because of an incomplete quotation system. On April 5, 1971, the National Association of Security Dealers Automatic Quotation (NASDAQ) system began including bid-and-ask quotations for 30 stocks listed on the New York Stock Exchange (NYSE); see Table 1.