WASHINGTON — Sales of previously occupied homes rose in 2009 for the first time in four years, despite a December slump that was due to a tax credit that led many buyers to complete sales earlier.

Still, prices plunged more than 12 percent last year — the sharpest fall since the Great Depression. The price drop for 2009 — to a median of $173,500 — showed the housing market remains too weak to help fuel a sustained economic recovery.

Concerns remain that home sales will weaken after March 31, when the Federal Reserve is set to end its program to buy mortgage securities to keep home loan rates low. Once that program ends, mortgage rates could rise. Adding to the worries, a newly extended homebuyer tax credit is set to run out at the end of April.

Some analysts question whether the housing market can remain stable without the hundreds of billions in government spending now propping it up.

Once the Fed's mortgage-buying program ends, analysts say rates could rise as high as 6 percent from the current level of around 5 percent for 30-year loans. That's why some expect the Fed to either extend or expand the program after March, concluding that the housing market remains too fragile.

"You just can't go from 100 miles an hour to a dead stop and expect it to happen without a big jump in mortgage rates," said Greg McBride, senior financial analyst at Bankrate.com.

DETROIT — Ed Whitacre Jr. says the main reason he's taking over as permanent CEO of General Motors Co. is to bring stability to the top of the troubled automaker.Whitacre, whose appointment was announced Monday, said although he's satisfied with the leadership team he's put in place, there's still work to do in sales and marketing, product development, purchasing and quality. Management experts say that means further changes and possibly more firings.GM's board asked Whitacre to stay on as CEO after seven weeks of searching for a successor from the outside. Whitacre, a former CEO of AT&T Inc., doesn't expect any more big shake-ups, but said he plans to rearrange middle management, which totals about 23,000 people, mainly in the U.S.