The Nasdaq Composite outperformed the S&P 500 and Dow Jones Industrial Average on Monday as biotech deal news helped push the index higher.
The Nasdaq gained 5 points, or 0.1%, to 4,774, helped by gains in biotech shares after XenoPort said it had reached a deal to sell itself to Arbor Pharmaceuticals for $7.03 a share.
The Dow industrials were flat, up less than 0.1% to 17,507, as gains from Apple Inc.(AAPL) and E.I. DuPont de Nemours & Co.(DD) offset losses from Exxon Mobil Corp.(XOM) and Microsoft Corp.(MSFT).
Meanwhile, the S&P 500 index fluctuated between gains and losses. It was down 2 points, or 0.1%, to 2,053 in recent trade.
Crude-oil prices tumbled, driving energy shares 0.7% lower, making it the index's worst-performing sector.
Materials shares rose 1.3% -- making it the S&P 500's best-performing sector -- as Bayer AG's(BAYN.XE)all-cash offer for Monsanto Co.(MON) lifted other chemicals companies.
With earnings season winding down, market strategists said investors would likely focus on remarks from a bevy of Federal Reserve officials slated to speak this week. Most importantly, Fed Chairwoman Janet Yellen is expected to speak on Friday.
According to indicators, including the fed funds futures market, the likelihood of a June rate hike moved substantially higher after minutes from the Fed's April meeting -- released on Wednesday -- showed a majority of voters felt a hike in June would be warranted if the economy continued to improve.
"The significance of the June meeting has only gained more importance after the Fed minutes last week," said Mohannad Aama, managing director at Beam Capital Management.
Equities closed higher on Friday, when the S&P 500 snapped a three-week losing streak to close up 0.3% last week. The Nasdaq Composite Index came off a four-week run of declines to gain 1.1%, but the Dow industrials extended a series of weekly losses to four, dropping 0.2%.
The dollar and oil prices were on the move Monday. A much-stronger-than-expected April trade surplus, which weighed on the dollar , sending it to Yen109.48 from Yen110.22 late Friday in New York. The Nikkei 225 index closed down 0.5% on yen strength.
At the same time, oil-field-services firm Baker Hughes Inc. reported Friday that the number of rigs drilling for oil in the U.S. was unchanged last week, while the number of oil rigs in the Permian Basin in West Texas rose. July WTI crude dropped 80 cents, or 1.7%, to $47.61 a barrel.
Fedspeak in focus: Boston Fed President Eric Rosengren said the U.S. is "on the verge" of meriting a June interest-rate hike, in an interview with the Financial Times that published on Sunday. Two weeks ago, he said rate increases should resume.
On the data front, a preliminary reading from the Markit flash PMI showed activity in the sector has been lackluster in May. The index came in at 50.5. Readings below 50 signal contraction.
St. Louis Fed President James Bullard got the ball rolling early Monday with a speech in Beijing on the economy and monetary policy. San Francisco Fed President John Williams said the election this fall wouldn't prevent the central bank from raising interest rates, and that a hike in June remains likely.
At 6:30 p.m. Eastern, Philadelphia Fed President Patrick Harker will speak on the economic outlook.
Stocks to watch:Boeing Co.(BA) slipped after Vietnamese carrier VietJet Aviation JSC said Monday that it had signed a $11.3 billion deal () to buy 100 planes from the U.S. airplane maker.
Other markets: Gold prices eased on Monday. Analysts at Citigroup said if the U.S. dollar index breaks through 100 again, gold prices could drop through $1,000 an ounce.
European stocks traded lower. In Asia, the Shanghai Composite Index rose 0.6%, while the Hang Seng Index dipped 0.2%.
By Joseph Adinolfi, MarketWatch, Barbara Kollmeyer