David B. Heller and Edward K. Eisler, two of the four co-heads of securities trading at Goldman Sachs Group, are leaving the firm as it grapples with declining revenue from the business.

Isabelle Ealet, 48, the bank’s London-based global head of commodities since 2007, will become one of three co-heads of the securities division alongside Pablo J. Salame, 45, and Harvey M. Schwartz, 47, according to one of three internal memos obtained by Bloomberg News. Michael DuVally, a spokesman for the New York-based company, confirmed the memos’ contents.

Goldman Sachs’ securities division handles sales and trading of equities, fixed-income, currencies and commodities. Heller, 44, Eisler, 42, Salame and Schwartz have overseen the business since 2008. Trading revenue, which was more than 60 percent of the firm’s total in the first nine months of 2011, dropped 22 percent from the same period a year earlier.

Separately, Goldman Sachs will pay $993,841 to settle a suit brought by a group of computer technicians who said they weren’t paid overtime for their work as contractors.

The parties asked US District Judge William H. Pauley in Manhattan in a filing yesterday to approve the settlement. Forty-one technicians returned claim forms, according to the filing.