Sullivan & Cromwell and Allen & Overy (A&O) are taking key advisory roles after the US Securities and Exchange Commission (SEC) on Friday (16 April) filed a civil suit accusing Goldman Sachs of securities fraud.

The suit, which claims Goldman created and sold a collateralised debt obligation (CDO) secretly designed to fail, is the first action taken by regulators against those that capitalised on the collapse of the US housing market.

Legal Week sister title Corporate Counsel reports that hedge fund Paulson & Co paid Goldman roughly $15m (£9.8m) to structure the CDO so that it could take short positions against mortgage securities that it helped choose. The SEC claims that while other investors lost almost $1bn (£656m) on the CDO, Paulson earned almost $1bn by betting against it.

When asked by reporters why Paulson was not sued, SEC enforcement director Robert Khuzami (pictured) said it was because Goldman was responsible for representations to investors, not Paulson.

Also named as a defendant in the SEC suit is Fabrice Tourre, a Goldman vice president who helped create and sell the mortgage investment. The New York Times previously reported that Tourre, a French trader at Goldman, was one of a handful of Wall Street traders that profited from betting against bad debt that banks bundled for investors.

Sullivan partner Richard Klapper is representing Goldman in the suit. The US firm has a longstanding relationship with the investment bank. A&O New York litigation partner Pamela Chepiga is representing Tourre.

Goldman shares fell 10% after the SEC announced the suit in a press release on Friday. The suit itself was brought by the SEC's structured and new products unit, one of the new divisions Khuzami promised to create after his appointment last summer.

The unit's chief, Kenneth Lench, is handling the case for the US Government along with a team of SEC lawyers.