By Kimberly Amadeo. NASDAQ originally stood for the National Association of Securities Dealer Automated Quotation system. Today, NASDAQ is the largest electronic equities exchange in the U.S. That's thanks to its 2008 merger with OMX ABO, a Stockholm-based operator of exchanges located in the Nordic and Baltic regions.The new company, NASDAQ OMX Group, lists stocks of over 3,800 companies.he NASDAQ is an exchange, like the New York Stock Exchange and the newly creates BATS. Unlike the NYSE, it also reports the performance of all the companies that have listed with it. The Dow, the S&P 500 and the MSC I are indices that track the performance of selected stocks.