By Kate Gibson

U.S. stock investors have found reason for cheer in recent data showing strength in home and car sales. But stock analysts caution that both markets have drawn short-lived boosts from government stimulus programs -- one of which ends Monday, the other at the end of November.

"The recent strength in home and car sales got a large boost from the transitory stimulus programs, and we worry that sales have been brought forward," said William O'Donnell, an analyst at RBS. "If Peter has in fact stolen from Paul, then some benchmark economic releases could look soggier as we hurtle toward year-end."

Housing- and car-sales data "continue to be skewed by government bailout efforts," said Paul Nolte, director of investments at Hinsdale Associates.

"What makes the data more concerning for the long-term viability of any recovery that we may be in the middle of is much of the [housing] activity came from distressed sales, inventories of unsold homes still rose, and home prices are still falling," said Nolte.

With the government's "cash for clunkers" program ending late Monday, "we'll now get to see what the natural supply and demand dynamic is in the auto industry," said Peter Boockvar, equity strategist at Miller Tabak & Co. .

Shares of Toyota Motor Corp. (TM) slipped 0.5%. The auto maker's Corolla was the top-selling model under the U.S. incentive program. Shares of Honda Motor Co. (HMC), which makes the Civic, the second-best-selling car under the program, tilted 0.2% lower, while Ford Motor Co.'s (F) Focus ranked third. Shares of Ford were down 5.1%.

T.J. Marta, chief market strategist at Marta on the Markets, said that while the "clunkers" program boosted sales and production, the gains came at least partly at the expense of future sales and production, both of which Marta said he expects to see fall "below even recent rates" in several months.

"The program interrupted the much-needed reallocation, or creative destruction, of excess capacity in the auto industry," said Marta.

And, the program prompted "lower-middle- and middle-class owners of older vehicles to lever up on debt and depreciate assets at a time when these people should be shoring up their balance sheets in the face of rising unemployment," the analyst added.

"The other major program, the 'cash for shelter' plan providing tax credits for home purchases, runs to Nov. 30, but there is already talk of enlarging its size and making it available to all home buyers, not just first-time," said Boockvar.

In a related note, Jeffrey Saut, an analyst at Raymond James & Associates, said autos and housing have typically been the engines that have pulled the economy out of past recessions.

But, since both are debt-driven sectors, Saut finds it difficult to envision them leading the charge this time around "given the consumer's current de-leveraging mindset," he said.

On Monday, stocks initially pulled higher for a fifth day in the wake of a report Friday that existing-home sales climbed more quickly than forecast. .

But by afternoon trade, the major indexes had fallen into the red, led by losses in the consumer discretionary sector -- led by Ford as well as Goodyear Tire & Rubber Co. (GT), with the latter off 6.2%.

At 1:30 p.m. Eastern, the Dow Jones Industrial Average (DJI) stood at 9,502.93, down 3.03 points. The S&P 500 Index (SPX) was off 1.34 points to 1,024.79, while the Nasdaq Composite (RIXF) had declined 5.24 points to 2,015.66.

"The persistent rise in the stock market may be signaling an end to the recession, or investors may be whistling past the graveyard," said Nolte of the market's trend upward.