Reuters.com reports a senior U.S. lawmaker urged the SEC to reinstate an index arbitrage rule to halt market volatility. "The SEC has the authority and responsibility to ensure that this volatility is not exacerbated dangerously by internal market mechanisms such as program trading which could push this situation into a free fall," said Democratic Rep. Edward Markey, who was chairman of the House subcommittee on telecommunications and finance during the market turmoil of the late 1980s. In a letter addressed to SEC Chairman Christopher Cox, Markey urged the SEC to order the New York Stock Exchange to reinstate rule 80A, which was designed to help calm market volatility.