Since the first issuance of an exchange-traded fund (the SPYDER S&P 500 ETF) on the American Stock Exchange in 1993, there has been steady growth in the number of firms providing ETFs in the U.S. market. At year end 2015, ETF's in the U.S. totaled 1594 funds holding 2.1 trillion dollars in net assets. The ETF marketplace is quite active, with new firms frequently entering and leaving (through acquisition, merger or liquidation) the marketplace.