* U.S. Fed has right monetary accommodation in place: Fed's Evans
* Dow, S&P briefly hits new session highs
* Yahoo's board approves $1.1 bln Tumblr acquisition
* Indexes: Dow off 0.2 pct, S&P off 0.2 pct, Nasdaq 0.3 pct
U.S. stocks slipped by afternoon trade on Monday as indexes struggled to break above their record levels with investors hesitant to rush into the market.
Trading was choppy, seesawing between modest gains and losses. Investors were eyeing comments from Chicago Federal Reserve Bank President Charles Evans, who said the Fed has the appropriate level of monetary accommodation in place, allowing the economy to reach "escape velocity" next year.
Earlier, the Dow climbed to an all-time intraday high at 15,391.84, while the S&P 500 edged up to a new intraday record high at 1,672.84. Both major indexes are up about 17 percent for the year so far. The S&P 500 is up more than 1,000 points from March 2009 lows.
Analysts say various benchmarks are battling key levels, which could hint at a bout of profit-taking on the horizon.
"Various benchmarks are taking aim at both round-number levels and round-number percentage gains above their respective 2009 lows. This may inspire profit-taking or, at least, hesitancy among the bulls," said Todd Salamone, director of research at Schaeffer's Investment Research in Cincinnati, Ohio.
The Dow Jones industrial average was down 28.57 points, or 0.19 percent, at 15,325.83. The Standard & Poor's 500 Index was down 3.24 points, or 0.19 percent, at 1,664.23. The Nasdaq Composite Index was down 9.16 points, or 0.26 percent, at 3,489.80.
The Dow industrials and the S&P 500 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.
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 0.6 percent at $26.67.
Actavis rose 1.7 percent to $127.66 after the company said it will acquire Warner Chilcott Plc in a stock-for-stock transaction valued at $5 billion. Warner Chilcott gained 2.9 percent to $19.77.
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 7.3 percent to $48.85, while Freeport gained 0.7 percent to $32.90, reversing an earlier decline.
Investors will get more comments from the Fed when Chairman Ben Bernanke's testifies before Congress on Wednesday.
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.