U.S. stocks rose on Monday as a flurry of merger news and solid earnings boosted investors' appetite for equities, pushing the Dow and the S&P 500 to their highest levels since June 2008.

Buying accelerated after the S&P 500 broke through the high end of its recent range, suggesting Wall Street has the strength to move the market higher.

What's helping us today are the fundamentals. M&A activities are a good sign for the stock market, and it's a 'feel good' momentum, said Ryan Detrick, senior technical analyst at Schaeffer's Investment Research in Cincinnati, Ohio.

The Dow Jones industrial average <.DJI> was up 82.50 points, or 0.68 percent, at 12,174.65. The Standard & Poor's 500 Index <.SPX> was up 10.19 points, or 0.78 percent, at 1,321.06. The Nasdaq Composite Index <.IXIC> was up 23.67 points, or 0.85 percent, at 2,792.97.

Diversified industrial company Danaher Corp agreed to buy medical diagnostics company Beckman Coulter Inc for about $6.8 billion and oil drilling company EnsCo Plc will buy rival Pride International Inc

for about $7.3 billion.

The deals suggested stock valuations are viewed as attractive. Danaher Corp rose 3.4 percent to $49.59 and Beckman Coulter rose 9.7 percent to $82.49.

EnsCo fell 4.5 percent to $51.91 while Pride International rose 15.8 percent to $39.84.

Loews Corp reported its best quarter of the year, posting a better-than-expected 16 percent jump in profit. The conglomerate's stock gained 4.8 percent to $43.40.

About 72 percent of S&P 500 companies that have reported results so far posted stronger-than-expected earnings, according to Thomson Reuters data. Investors expect aggregate earnings rose 37 percent in the last quarter, the highest estimate for that period in more than 10 months.

Adding to Wall Street's image problem, Nasdaq OMX Group said on Saturday that computer hackers had infiltrated the operator of the Nasdaq Stock Exchange.

Hacking is going to be a global problem and like a war breaking out, it is hard to hedge against it. There will be concerns, but it's not going to have an impact on how investors see opportunities for the stock market, said Joe Battipaglia, market strategist at a private client group for Stifel Nicolaus in Philadelphia.

Struggling U.S. Internet company AOL Inc has agreed to buy The Huffington Post, the rapidly growing news, analysis and lifestyle website, for $315 million. AOL shares fell 1.1 percent to $21.70.

UBS raised its 2011 target for the S&P 500 index by 7.5 percent to 1,425 from 1,325, citing an improving outlook for the economy and earnings.

(Reporting by Angela Moon, Editing by Kenneth Barry)