The large acquisitions, combined with generally positive third-quarter earnings news, "should help buoy investors’ sentiment," said John C. Forelli, portfolio manager for Independence Investment LLC in Boston.

"It’s sort of merger mania today," Forelli said. "My guess is once investors look at this, they’ll become more optimistic that there will be some more merger activity in corporate America."

In afternoon trading, the Dow Jones industrial average was up 44.45, or 0.5 percent, at 9,626.91, after falling 1.4 percent last week.

The broader gauges were also higher. The Nasdaq composite index rose 17.23, or 0.9 percent, to 1,882.82, following a weekly decline of 2.5 percent. The Standard & Poor’s 500 index was up 4.00, or 0.4 percent, at 1,032.91, having shed 1.7 percent the previous week.

There was also positive news out of Washington. A Commerce Department report showed a dip in new-home sales last month, but the level of sales was stronger than forecast — a sign that the housing market continues to help spur an economic recovery.