US STOCKS-Dow, S&P fall on debt worries; semis lift Nasdaq

* Tyson Foods posts better-than-expected profit

* SanDisk, semis, lift Nasdaq

* Dow off 0.5 pct, S&P off 0.4 pct, Nasdaq up 0.3 pct

* For up-to-the-minute market news see [STXNEWS/US] (Updates to midmorning)

By Chuck Mikolajczak

NEW YORK, Nov 22 (Reuters) - The Dow and S&P 500 fell on Monday as enthusiasm over a bailout package for Ireland faded and investors worried that further steps would be needed to combat euro zone sovereign debt problems.

The European Union and International Monetary Fund began to thrash out details of a loan package to Ireland to resolve its banking and budget crisis. For details, see [ID:nLDE6AL00M]

Concerns that Ireland's debt crisis might spread to other euro zone countries has hung over U.S. stocks in recent weeks. World shares pulled back from an early rise, while European markets fell 0.7 percent on Monday.

U.S.-listed shares of Bank of Ireland tumbled 16.1 percent to $2.24, and Allied Irish Banks Plc lost 1.6 percent to $1.21.

"A Band-Aid is not what is needed, major surgery is what is needed. Money is not going to solve the problem," said Peter Kenny, managing director at Knight Equity Markets in Jersey City, New Jersey.

"All you are doing is buying time. You are kicking the can down the road. We are finally coming to terms with the fact you can't keep kicking the can down the road."

The euro fell 0.4 percent against the dollar on fears about possible contagion to other highly indebted euro zone nations. [ID:nN22267428]

The Dow Jones industrial average <.DJI> dropped 51.84 points, or 0.46 percent, to 11,151.71. The Standard & Poor's 500 Index <.SPX> lost 4.50 points, or 0.38 percent, to 1,195.23. The Nasdaq Composite Index <.IXIC> gained 6.17 points, or 0.25 percent, to 2,524.29. The Nasdaq was boosted by strength in the semiconductor sector after Robert W. Baird upgraded SanDisk Corp shares to "outperform" from "neutral." [ID:nSGE6AL0MY]

SanDisk gained 5.6 percent to $42.26, while the PHLX Semiconductor index <.SOX> rose 0.7 percent.

Trading volume is expected to be tepid this week due to the U.S. Thanksgiving Day holiday on Thursday.

No. 1 U.S. meat producer Tyson Foods Inc posted higher-than-expected quarterly profit on a big jump in gross margins and said its current quarter was off to a strong start. Its shares gained 3 percent to $16.11. [ID:nSGE6AL0N3]

Quarterly results are due from Hewlett-Packard Co and Analog Devices Inc after the close. (Editing by Jeffrey Benkoe)