I've been hammering on this issue too with PNCH and other stocks. As you undoubtedly know, TDA helped bail out Knight after the trading debacle last August. Since the rescue, TDA has been suspending online buys of certain issues and the evidence seems to be growing that NITE is shorting its way out of financial trouble with TDA's help. Artificial supply & demand. Hope FINRA nails both TDA and Knight.