Eventual losses at mortgage giant Fannie Mae (FNM) could exceed $200bn, posing a risk of receivership after year-end when limitations on the Treasury Department's authority to support the agencies return, according to research Friday by Barclays Capital (BarCap). Once the added authority expires, the Treasury will no longer be able to increase the size of the $200bn preferred backstops supporting Fannie and brother agency Freddie Mac (FRE) without consulting Congress. BarCap researchers recommended the Treasury increase the size of the preferred stock purchase agreements now to avoid the risk of losses breaching the $200bn limit. Otherwise, BarCap said, receivership might be triggered. "Nationalization is not an immediate option, as putting FNM/FRE on the government’s balance sheet would increase public debt outstanding by $2trn, further straining perceptions of fiscal responsibility," researchers said. "Mid-term elections next year also make it likely that any drastic steps that threaten the fragile housing recovery will be stymied." Write to Diana Golobay.