The Securities and Exchange Commission is investigating whether traders spread misinformation in a bid to drive down shares of financial firms, according to an SEC subpoena, USA Today reports Thursday. Served on numerous hedge funds, the subpoena identifies two former investment banks -- Bear Stearns and Lehman Brothers -- that the SEC believes may have been subject to short-selling manipulation, the newspaper reports. The subpoena seeks internal trading data, personnel information and e-mail and other communications relating to market rumors in June and July. Among the rumors were that Lehman would get access to the Federal Reserve Bank's discount window, British bank Barclays ( BCS) would buy Lehman for $15 a share (its market price was near $20), and that investment firms SAC Capital and Pimco had stopped trading with Lehman, USA Today reports. Bear Stearns, suffering from a liquidity crisis, was taken over by JPMorgan Chase ( JPM), while Lehman was forced to file for bankruptcy and has sold its core trading operation to Barclays.