%u201CIneffective regulation allowed the failure of A.I.G. Financial Products and the derivative dealers affiliated with Lehman Brothers, Bear Stearns and investment banks to affect the entire financial system,%u201D Gary Gensler, the trading commission%u2019s chairman, said in testimony before the House Financial Services Committee on Wednesday. %u201CWe must ensure that this never happens again. We cannot afford any more multibillion-dollar bailouts.%u201D