Healthcare and energy stocks drove gains on Wall Street on Wednesday ahead of the release of minutes from the U.S. Federal Reserve's meeting on interest rates in March.

Investors, who have been grappling with mixed signals on rate hikes from Fed officials, will parse the minutes to gain insight into the central bank's thinking on the economy. The minutes are due at 2 p.m. ET (1600 GMT).

The collapse of the $160 billion merger of Pfizer and Allergan bolstered the healthcare sector on rising hopes that the pharmaceutical giants could turn to smaller targets.

Pfizer shares rose 3.9 percent to $32.57 and gave the biggest boost to the S&P 500, while Allergan was up 3.6 percent at $245.05.

Crude jumped nearly 5 percent after data showed an unexpected draw in U.S. crude stockpiles last week. [O/R]

A seven-week rally - sparked by rising oil, strength in the economy and a cautious Fed - helped stocks recover from a steep selloff that had sent the S&P 500 down more than 10 percent earlier this year. The index closed flat for 2016 on Tuesday.

"We're still technically in a declining environment, and we have to get to an all-time high before we can give the all-clear signal," said Sam Stovall, U.S. equity strategist at S&P Global Market Intelligence in New York.

Stovall said better-than-expected corporate earnings could provide the catalyst to drive stockshigher that investors were looking for.

S&P 500 companies on average are expected to report a 7.4 percent fall in first-quarter earnings, according to Thomson Reuters I/B/E/S.

At 12:48 p.m. ET (1648 GMT), the Dow Jones industrial average <.DJI> was up 68.15 points, or 0.39 percent, at 17,671.47, the S&P 500 <.SPX> was up 13.25 points, or 0.65 percent, at 2,058.42 and the Nasdaq Composite <.IXIC> was up 49.43 points, or 1.02 percent, at 4,893.36.

Seven of the 10 major S&P sectors were higher, led by a 2.09 percent rise in energy <.SPNY>. The sector is up 2.5 percent in 2016, having tracked the rebound in crude.

The S&P healthcare <.SPXHC> sector, which was up 2.03 percent on Wednesday, is one of only two sectors in negative territory for the year.

Advancing issues outnumbered decliners on the NYSE by 2,108 to 814. On the Nasdaq, 1,851 issues rose and 803 fell.

The S&P 500 index showed eight new 52-week highs and no new lows, while the Nasdaq recorded 24 new highs and 15 new lows.