U.S. investors were unwilling to make big bets early Monday after four weeks of big gains. Yahoo could draw attention after officially announcing a $1.1 billion deal to buy blogging site Tumbler.

U.S. stock futures were barely lower ahead of the open. But shares of Yahoo (YHOO) slumped after the Tumblr deal was made official. Earlier, shares were up more than 2%.

Actavis (ACT) shares jumped after the drug company it would buy Warner Chilcott (WCRX) in an $8.5 billion stock-for-stock transaction.

Chesapeake Energy (CHK) shares edged up after the natural gas and oil producer announced its new CEO would be Robert Douglas Lawler, an executive at Anadarko Petroleum (APC).

A few companies are still expected to report quarterly results Monday.

Campbell Soup (CPB) reported quarterly earnings that beat expectations ahead of the market open.

TiVo (TIVO)reports in the afternoon.

Home Depot (HD), Best Buy (BBY), Target (TGT) and Hewlett-Packard (HPQ) are due later in the week.

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Deutsche Bank analyst Jim Reid said that Federal Reserve Chairman Ben Bernanke's testimony on economic outlook, scheduled for Wednesday before the Joint Economic Committee, "will be the highlight in a week where we may learn more about the Fed's intentions with regards to potential [quantitative easing] tapering."

U.S. stocks finished higher Friday, with the Dow and S&P 500 ending at record levels.

The three major U.S. indexes have gained around 16% so far this year on a combination of gradually improving economic data and continued support from the Federal Reserve.

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European markets were mostly higher in midday trading. Germany's DAX was leading the indexes forward.

Meanwhile Asian markets ended with significant gains. The Shanghai Composite added 0.8%, the Nikkei advanced 1.5% and the Hang Seng increased 1.8%. The Nikkei is at its highest point in about five years.