* Caterpillar lifts outlook, shares jump 10 percent
* Fed chairman Bernanke cautious about economy (Recasts, updates to mid-morning)
By Rodrigo Campos
NEW YORK, July 21 (Reuters) - U.S. stocks rose slightly on Tuesday as upbeat quarterly results from bellwether companies, including Caterpillar Inc, overshadowed Federal Reserve Chairman Ben Bernanke's cautious outlook for the economy.
The Dow industrials held on to early gains as Caterpillar shares soared more than 10 percent to $40.62, following results and an upbeat outlook by the world's largest maker of mining and construction vehicles.
Bernanke said in testimony to a House of Representatives committee that job insecurity, together with declines in home values and tight credit, is likely to limit gains in consumer spending -- a key driver of the U.S. economy.
"(Bernanke) sees what he calls 'tentative signs of stabilization,' but he remains very cautious about calling this a recovery," said Hugh Johnson, chief investment officer at Johnson Illington Advisors in Albany, New York.
The Dow Jones industrial average gained 56.23 points, or 0.64 percent, to 8,904.38. The Standard & Poor's 500 Index edged up 0.90 points, or 0.09 percent, to 952.03. The Nasdaq Composite Index shed 4.37 points, or 0.23 percent, to 1,904.92.
The S&P 500 closed at an eight-month high on Monday, as the early stages of a healthier-than-expected second quarter earnings season lifted investors' hope about the economic recovery.
After the closing bell on Monday, chipmaker Texas Instruments Inc posted a stronger-than-expected second-quarter operating profit, but its stock slipped more than 3 percent to $22.90.