U.S. stocks slipped on Monday, as an early bounce on Osama bin Laden's death gave way to questions around the longevity of the market's recent rally.

The impact of bin Laden's death by U.S. forces on financial markets prompted a quick flurry of buying, which was viewed as an emotional response. The Dow swung 92 points from its high of the day to its low.

His death should not have affected the markets much ... (but) just people feeling a little better about the world sometimes impacts the stock market, said Bryant Evans, investment adviser and portfolio manager at Cozad Asset Management, in Champaign, Illinois.

Energy and materials were the weakest performers. Investors pulled back from shares that have outperformed lately following declines in commodities. The S&P energy index <.GSPE> was down 1.3 percent.

U.S. crude prices ended lower but were off the sharp declines that immediately followed word of the al Qaeda leader's killing, and silver dipped after a recent rally.

Monday's fall followed the Dow's and Nasdaq's posting their best monthly gains since December, and analysts forecast little resistance for the S&P 500 until 1,400.

We've seen a great stock market this year, and that shows you that the broader economy is what's important, Evans said.

Stocks also were helped by merger and acquisition announcements, which often reflect optimism about the longer-term outlook. The S&P 500 is up 30 percent since the start of September, roughly when the current rally began.

The Dow Jones industrial average <.DJI> was down 3.18 points, or 0.02 percent, at 12,807.36. The Standard & Poor's 500 Index <.SPX> was down 2.39 points, or 0.18 percent, at 1,361.22. The Nasdaq Composite Index <.IXIC> was down 9.46 points, or 0.33 percent, at 2,864.08.

The CBOE Volatility Index, Wall Street's fear gauge, rose 8.8 percent. The VIX index, which often moves inversely to the S&P 500, measures the cost of hedges or protection investors are willing to pay against a fall in the S&P 500.

Among the deal news, Israel-based Teva Pharmaceuticals Industries Ltd will buy Cephalon Inc for $6.8 billion, and Arch Coal Inc will acquire International Coal Group Inc for $3.4 billion.

U.S.-listed shares of Teva rose 3.4 percent to $47.27, while Cephalon gained 4 percent to $80.11. Arch shares were down 2.2 percent at $33.53, but International Coal soared 30.8 percent to $14.43 and was the among the most actively traded stocks on the New York Stock Exchange.

In addition, Community Health Systems Inc raised its bid for Tenet Healthcare Corp by $1.75 per share to $7.25.

Community Health fell 1.7 percent to $30.22, and Tenet dropped 3.5 percent to $6.69.

In other deal news, Nasdaq OMX Group and IntercontinentalExchange Inc took their $11 billion takeover bid for NYSE Euronext directly to the Big Board's shareholders with a tender offer. NYSE shares were up 0.8 percent at $40.40, while Nasdaq shares were up 0.07 percent at $27.14.

About 7.35 billion shares traded on the New York Stock Exchange, NYSE Amex and Nasdaq, below last year's estimated daily average of 8.47 billion.

Declining stocks outnumbered advancing ones on the NYSE by a ratio of 3 to 2, while on the Nasdaq, about 9 stocks declined for every 4 that rose.

(Reporting by Caroline Valetkevitch; Editing by Kenneth Barry)