US Stocks rally for third day, Dow jumps 178 (ext)

NEW YORK (CNNMoney) -- U.S. stocks rallied for a third day on Monday, as fears about Japan's damaged nuclear plants eased and investors cheered a huge merger in the telecommunications industry.

The Dow Jones industrial average (INDU) jumped 178 points, or 1.5%, to 12,037. It's the first time the Dow has closed above the 12,000-point mark since the day of the Japanese earthquake on March 11.

The S&P 500 (SPX) index added 19.2 points, or 1.5%, to 1,298; and the tech-heavy Nasdaq (COMP) gained 48 points, or 1.8%, 2,692.

Stocks spiked at the open Monday, and remained steadily higher throughout the session.

Aside from corporate news, investors continue to react to developments in Japan and Libya.

Over the weekend, Japanese engineers made progress in cooling nuclear reactors that had overheated, following the devastating earthquake and tsunami that struck the country March 11.

Meanwhile, turmoil in North Africa heated up. The United States and its allies launched an airstrike on Libyan military targets Monday, in an effort to subdue forces of Libyan leader Moammar Gadhafi.

Oil prices jumped more than $1 a barrel in electronic trading, following the attack.

"The fear of a Middle East contagion and a horrible nuclear calamity in Japan has abated, and the good news is that the economy and market fundamentals have returned to the forefront," said Paul Zemsky, head of asset allocation with ING Investment Management.

The dollar gained against the euro and the Japanese yen, but was flat versus the British pound.

Gold futures for April delivery rose $10.30, or 0.7%, to $1,426.40 an ounce.