ETFs have been available to investors in the United States since 1993, and to European investors since 1999. Although index funds from their inception were allowed to track various market indexes, it was not until 2008 that the SEC allowed ETFs to be more actively managed, allowing managers of ETFs to purchase investments that appear to be undervalued or to sell short investments that may be overvalued, as indicated by share prices that may be falling in the near term.