NEW YORK (TheStreet) -- It was a hard slog for Wall Street Monday with markets unable to extend last week's surge even as a decline in the U.S. dollar gave extra impetus to a rally.

At the close, stocks slumped with the S&P 500I:GSPC down 0.17% and the Dow Jones Industrial AverageI:DJI down 0.06%. The NasdaqI:IXIC spent much of the day in the red on weakness in the pharmaceutical sector.

The U.S. dollar continued to fall, adding to its worst drop in more than three years last week. The greenback fell from 12-year highs last week after the Fed suggested a slower-than-expected rate hike timeline. The U.S. dollar fell 1.3% against the euro, 1.5% against the Aussie dollar, and 1.1% against the Swiss franc.

The lower dollar did have the benefit of boosting crude prices. West Texas Intermediate crude, which is denominated in U.S. dollars, was pushed 1.6% to $47.32 a barrel as cheaper exchange rates were seen as encouraging international demand. 

The energy sector moved higher on recovering oil prices. Major oil companies Exxon Mobil (XOM) - Get Report, Royal Dutch Shell (RDS.A) , Total (TOT) - Get Report and BP (BP) - Get Report were all higher.

Comments from the Federal Reserve Vice Chairman Stanley Fischer kept investor focus on the likelihood of a rate hike this year. Addressing the Economic Club of New York on Monday, Fischer said the Fed's first rate hike in 9 years would likely happen this year once inflation shows signs of improvement. The comments echoed the Fed's vow of data dependence last week.

"Monday's Fed-speak confirmed the market's perception of a more cautious FOMC in the wake of last week's meeting," said CRT Capital's Ian Lyngen. "Fischer acknowledged that liftoff ... will most likely be 'warranted before the end of the year' -- a fact priced in the Fed Funds futures market, but he offered little more in terms of timing."  

Existing home sales climbed 1.2% to 4.88 million in February. The reading fell slightly short of economists' estimates of an increase to 4.94 million from 4.82 million in January. The median sales price climbed to $202,600, up 7.5% from a year-earlier, and its biggest gain in a year.

Gilead Sciences (GILD) - Get Report dragged on the Nasdaq on reports the company had sent out warnings for hepatitis C drug Sovaldi to health providers, advising against using in conjunction with certain heart treatments. Nasdaq components Celgene (CELG) - Get Report, Vertex Pharmaceuticals (VRTX) - Get Report and RegeneronPharmaceuticals (REGN) - Get Report were also lower.

Monsanto (MON) , producer of agricultural products, pulled lower on Monday after the World Health Organization warned that its weed killer was carcinogenic, though the company rebutted the claims. Shares were down 1.7%.

Facebook (FB) - Get Report added 0.8% after having its price target increased to $97 from $94 at JMP Securities. Analysts said the boost was based on the social network's improving market share.

Lumber Liquidators (LL) - Get Report slid 2.2% after Senator Chuck Schumer called for the Consumer Product Safety Commission to launch a federal investigation into product safety. The company's flooring products have been brought under scrutiny after a 60 Minutes report alleged an unsafe level of formaldehyde.

Tenet Healthcare (THC) - Get Report spiked more than 5% after forming a joint venture with United Surgical Partners with the option of buying the company in 2020. Tenet will pay $425 million for a majority stake in the venture.