* Merck drops after results; Biogen climbs
* Apple shares volatile after the bell following results
* Dow down 0.01 pct, S&P 500 up 0.1 pct, Nasdaq down 0.1 pct
The S&P 500 closed at another record high on Monday as expectations were high that the Federal Reserve will keep its stimulus in place when it meets this week.
But the overall market was little changed, with the Dow and Nasdaq ending down slightly, after the recent sharp run-up in the stock market lost some momentum.
The S&P 500 has risen 6.4 percent since Oct. 8, when it hit its lowest point during the U.S. government's partial shutdown and the debate over raising the debt ceiling. The benchmark index is up 23.6 percent for the year so far.
Relief over the end of the political impasse and investor expectations that the Fed will keep stimulus measures in place for at least several months because of the 16-day shutdown have propped up prices. Fed policymakers will meet on Tuesday and Wednesday.
"I would like to say it's all about people waiting for the Fed, but I don't know what they're waiting for because I don't expect any change in Fed policy this week, given the fact they pointed out repeatedly the fiscal issues they're cognizant of," said Mark Luschini, chief investment strategist at Janney Montgomery Scott in Philadelphia.
"My concern with the market at this level is that without signs eliciting some evidence the economy is actually strengthening from the pace we've had, the multiple expansion doesn't seem rational."
Shares of Apple Inc rose 0.7 percent to $529.88 ahead of the release of its earnings, expected after the bell. While Apple's advance helped the S&P 500, the consumer staples sector index, up 1.2 percent, gave the S&P its biggest boost.
A number of traders appeared to be picking up call options on the Consumer Staples Select Sector SPDR fund, which rose 1.3 percent, on hopes that the sector will continue to perform well through the end of the year.
The Dow Jones industrial average dipped 1.35 points, or 0.01 percent, to end at 15,568.93. The Standard & Poor's 500 Index gained 2.34 points, or 0.13 percent, to finish at a record 1,762.11. The S&P 500 also posted another lifetime intraday high at 1,764.99.
The Nasdaq Composite Index slipped 3.23 points, or 0.08 percent, to close at 3,940.13.
In extended-hours trading, Apple's shares were flat after recovering from a 5 percent drop following the tech bellwether's results. Wall Street had hoped for a stronger beat on quarterly sales after the iPhone maker predicted in September that its revenue and margins would come in at the high end of its own forecasts.
Apple's stock price has climbed 8.8 percent since the end of August.
Among the latest signs that the economy's momentum may be easing, U.S. manufacturing output barely rose in September and contracts to buy previously owned homes recorded their largest drop in nearly 3-1/2 years, according to economic data released on Monday.
On the down side, Dow component Merck & Co fell 2.6 percent to $45.35 and was one of the biggest drags on the Dow after the company reported a decline in sales of its Januvia diabetes treatment, raising concerns about growth prospects for its biggest product.
Biogen Idec posted a rise in its third-quarter profit and boosted its full-year earnings and revenue outlook, sending the U.S. biotech company's stock up 0.9 percent to $254.43.
Based on Thomson Reuters data through Monday morning, S&P 500 earnings are expected to have risen just 3.4 percent in the third quarter over the year-ago period.
Of the 249 companies in the S&P 500 that have reported earnings so far, 69.1 percent beat analysts' expectations, above both the 63 percent beat rate since 1994 and the 66 percent rate for the past four quarters.
Revenue has been lackluster, however, with growth seen at 2.2 percent for the quarter. Just 53.9 percent have beaten sales estimates, below the 61 percent rate since 2002, but above the 49 percent rate for the past four quarters.
On the acquisition front, Mosaic Co agreed to buy CF Industries Holdings Inc's phosphate mining and manufacturing business for $1.2 billion in cash. Shares of CF climbed 4.2 percent to $218.36 while Mosaic gained 1.6 percent to $46.67.