* Alcoa to buy RTI International for $1.5 bln
* Apple shares end up slightly after Apple Watch roll out
* Indexes up: Dow 0.8 pct, S&P 0.4 pct, Nasdaq 0.3 pct (Updates to close)
By Caroline Valetkevitch
NEW YORK, March 9 (Reuters) - U.S. stocks bounced back on Monday, helped by merger and acquisitions activity, while Apple shares ended slightly higher following the long-anticipated rollout of its watch.
Alcoa Inc said it would buy RTI International Metals Inc for $1.5 billion. Separately, Shopping mall owner Simon Property Group offered to buy Macerich Co for $22.4 billion including debt.
Alcoa lost 5.4 percent to $13.70 while RTI jumped 39.3 percent to $38.00. Macerich rose 7 percent to $92.76 and Simon Property was down 0.1 percent at $180.44.
The day's gain came after the S&P 500's biggest drop in almost two months on Friday, when investors bet a stronger-than-expected U.S. jobs report increased chances the Federal Reserve could raise interest rates sooner.
"We're seeing a little bit of a snapback from Friday's reaction to the jobs report. We're seeing a little of that reversion-to-the-mean trade," said Larry Peruzzi, senior equity trader at Cabrera Capital Markets Inc in Boston.
Shares of Apple ended up 0.4 at $127.08 after trading both sides of unchanged as details of its watch were released, including that the price would range from $349 to more than $10,000.
"I just don't know if it's going to be the power product that everyone's looking for," said Daniel Morgan, senior portfolio manager at Synovus Trust Company in Atlanta.
The Dow Jones industrial average rose 138.94 points, or 0.78 percent, to 17,995.72, the S&P 500 gained 8.17 points, or 0.39 percent, to 2,079.43 and the Nasdaq Composite added 15.07 points, or 0.31 percent, to 4,942.44.
The S&P 500 is about 1.8 percent below its record closing high from last week, while the Dow is about 1.6 percent below its record.
Other top gainers included Whiting Petroleum Corp, which rose 10.8 percent to $37.71. Late Friday, the Wall Street Journal reported that the company was seeking a possible buyer, though a person familiar with the board's thinking told Reuters he was not aware of such a plan.
General Motors' shares rose 3.1 percent to $37.66 after it said it plans a new, $5 billion share buyback in an agreement with dissident investors, and put forward more details on capital allocation that promises investors the potential for further cash returns.
Shares of Qualcomm were up 2.3 percent at $74.40 after the bell following its announcement of a $15 billion share buyback.
About 6.2 billion shares changed hands on U.S. exchanges, below the 6.6 billion average for the last five sessions, according to BATS Global Markets.
Advancing issues outnumbered declining ones on the NYSE by 1,612 to 1,445, for a 1.12-to-1 ratio; on the Nasdaq, 1,521 issues rose and 1,215 fell, for a 1.25-to-1 ratio favoring advancers.
The S&P 500 posted eight new 52-week highs and 13 new lows; the Nasdaq Composite recorded 63 new highs and 65 new lows. (Editing by Bernadette Baum and Nick Zieminski)