Assured Guaranty, the Bermuda-based bond-insurer downgraded by Moody’s Investors Service in January, has created a new unit to back the debt of American states and cities.Assured and other insurers are currently is on the hook for at least 95 percent of the $2 billion of unsecured Detroit debt that wasn’t issued for city utilities, Bloomberg reported yesterday. Bloomberg said Detroit’s bid to stick investors with losses as part of an effort to avert a historic bankruptcy was “jeopardising municipal bond insurers’ recovery prospects”. It said Kevyn Orr, the city’s emergency financial manager, proposes paying investors less than 20 cents on the dollar on those bonds as the auto-industry capital bleeds cash.Meanwhile, Assured said in a statement that its Municipal Assurance Corp was started with $800 million of cash and securities contributed by two other Assured units and an agreement with those subsidiaries to reinsure $103 billion of muni bonds that allowed it to set up reserves of $709 million of unearned premium.The new unit was graded AA+ by Kroll Bond Rating Agency, that firm’s second-highest ranking, and two steps lower at AA-by Standard & Poor’s, the ratings companies said in separate statements.Municipal Assurance will guarantee “lower-risk categories” in the US public finance market, Kroll said in its statement.Moody’s cut its ratings on Assured Guaranty Municipal Corp. two levels to A2, its sixth-highest rating, from Aa3 in January. Another unit, Assured Guaranty Corp., was lowered three steps to A3.