"But decisions made at a brief meeting on April 28, 2004, explain why the problems could spin out of control. The agency's failure to follow through on those decisions also explains why Washington regulators did not see what was coming. On that bright spring afternoon, the five members of the Securities and Exchange Commission met in a basement hearing room to consider an urgent plea by the big investment banks. They wanted an exemption for their brokerage units from an old regulation that limited the amount of debt they could take on. The exemption would unshackle billions of dollars held in reserve as a cushion against losses on their investments. Those funds could then flow up to the parent company, enabling it to invest in the fast-growing but opaque world of mortgage-backed securities; credit derivatives, a form of insurance for bond holders; and other exotic instruments."
Stephen Labaton. "Agency's '04 Rule Let Banks Pile Up New Debt, and Risk: plans to increase S.E.C. Scrutiny of Firms Faltered." The New York Times 10/3/2008. A1.