A forum intended to debate the future of the Securities and Exchange Commission turned last week into a gripe session about problems the SEC must tackle in the present, as Chairman Christopher Cox called for new powers to regulate the credit derivatives that have shattered Wall Street.

Speaking at what originally had been billed as a roundtable to discuss the SEC’s 21st Century Disclosure Initiative, Cox pleaded that Congress grant his agency and the Commodities Futures Trading Commission power to regulate credit default swaps. Repeating a concern he aired in testimony before the Senate Banking Committee on Sept. 23, Cox ...