* Yahoo's board approves $1.1 bln Tumblr acquisition
* Plains Exploration stocks up as Freeport sweetens deal
* Actavis to acquire Warner Chilcott in stock-for-stock deal
* Dow off 0.04 pct, S&P up 0.01 pct, Nasdaq up 0.01 pct
By Leah Schnurr
NEW YORK, May 20 (Reuters) - U.S. stocks were little changed on Monday as acquisition activity gave support but investors were reluctant to rush into the market with indexes hovering around record levels.
Deals including Yahoo's $1.1 billion bid for Tumblr indicate that companies continue to search for growth through acquisitions, a bullish sign for stocks. Yahoo was up 0.8 percent at $26.73.
The S&P 500 and Dow industrials finished Friday at fresh record highs and the Nasdaq Composite is at its highest since late 2000. A light economic and earnings calendar could leave the market vulnerable for a pullback, but those have been shallow and short-lived as investors take any weakness as a new chance to increase long positions.
On Monday, the S&P 500 notched a new intra-day high at 1,668.70.
Some consolidation "will let things settle down a little bit after a white-hot two week period for the stock market," said Fred Dickson, chief market strategist at D.A. Davidson & Co in Lake Oswego, Oregon.
"Traders are stepping back, reassessing valuation levels on their positions."
Actavis rose 3.3 percent to $129.63 after it said it
will acquire Warner Chilcott Plc in a stock-for-stock transaction valued at $5 billion. Warner Chilcott gained 4.1 percent to $19.99.
The Dow Jones industrial average slipped 5.91 points, or 0.04 percent, to 15,348.49. The Standard & Poor's 500 Index added 0.20 points, or 0.01 percent, to 1,667.67. The Nasdaq Composite Index gained 0.29 points, or 0.01 percent, to 3,499.26.
Freeport-McMoRan Copper & Gold and Plains Exploration & Production said they would pay shareholders more in dividends if they approved Freeport's roughly $6 billion takeover offer for Plains. Plains shares jumped 7.2 percent to $48.81, though Freeport slipped 1 percent to $32.35.
Websense Inc shares jumped 28.6 percent to $24.74 after it agreed to be acquired by Vista Equity Partners.
Solar products maker JA Solar Holdings reported another quarterly loss on lower prices for panels that convert sunlight into electricity, but its operating loss nearly halved from the first quarter of 2012. Its shares shot up 45.5 percent at $6.16.
Federal Reserve chairman Ben Bernanke's testimony before Congress on Wednesday is seen by many as the highlight of the week for markets. The beginning of the end of the Fed's massive bond-buying program, which has given strong support to stock gains, might come sooner than many investors think if recent gains in the U.S. labor market hold.
The Fed will also release minutes from its most recent policy-setting meeting on Wednesday, which will be parsed for signs of the direction of monetary stimulus.