U.S. Mortgage Rates Rise to 5.2%, Freddie Mac Says  July 23 (Bloomberg) -- Mortgage rates in the U.S. rose for the first time in four weeks, a sign the federal government’s effort to lower borrowing costs is losing momentum. The average 30-year rate increased to 5.2 percent from 5.14 percent, mortgage buyer Freddie Mac of McLean, Virginia, said today in a statement. The 15-year rate was 4.68 percent. Mortgage rates fell to the lowest since May last week, driven down by the Federal Reserve’s $1.25 trillion plan for buying mortgage-backed securities. Falling rates helped boost refinancing and purchase applications for home loans. The yield on the 10-year Treasury note also declined earlier this month to the lowest since May. Federal Reserve Chairman Ben S. Bernanke is trying to lower borrowing costs with a program to purchase securities backed by home loans. Delinquent mortgages triggered the global credit crunch and have cost financial firms almost $1.5 trillion in losses and asset write downs so far, according to data compiled by Bloomberg. Mortgage rates reached a record low 4.78 percent twice in April after the central bank announced its plan to boost buying of both mortgage securities and Treasuries. Those purchases brought down yields on government debt and mortgage-backed bonds issued by Fannie Mae, Freddie Mac and Ginnie Mae, allowing lenders to reduce rates on new loans and still sell the securities at a profit. Rates started climbing in May along with Treasury yields on investor concern that higher government debt would fuel inflation. Higher rates may counter signs that the housing market is stabilizing. U.S. home prices had the smallest annual drop in 10 months in May, the Federal Housing Finance Agency in Washington said yesterday. Prices declined 5.6 percent in May from a year earlier and rose 0.9 from April, a sign the free fall of property values is abating in the three-year housing slump at the center of a global recession. The Mortgage Bankers Association’s index of home loan applications rose 2.8 percent to 528.9 in the week ended July 17. Purchase applications rose 1.3 percent and requests to refinance gained 4 percent.