NEW YORK (TheStreet) -- Stocks were moving lower on Monday with a selloff among energy and homebuilder stocks offsetting gains in health care. 

The S&P 500 was down 0.31%. The Dow Jones Industrial Average fell 0.37%, and the Nasdaq slid 0.25%, weighed down by declines in Tesla (TSLA .

Crude oil dropped below $50 a barrel again, as the U.S. dollar strengthened. West Texas Intermediate fell 2.3% to $49.64 a barrel, while the U.S. dollar gained 0.37% against the euro and more than 1% against the Swiss franc.

Energy shares were lagging the market. Oil giants Exxon Mobil (XOM , Chevron (CVX , Halliburton (HAL and Schlumberger (SLB were all lower, while the Energy Select Sector SPDR ETF (XLE slid 0.61%.

Tesla was more than 4% lower after Bank of America reiterated an "underperform" rating and cut its price target to $65 from $70 a share. The firm said the alternative automaker has been focusing on long-term targets when it should be focusing on shorter-term results.

Health care was higher, led by Valeant Pharmaceuticals (VRX which popped nearly 15% after agreeing to buy to buy Salix Pharmaceuticals (SLXP for $10.1 billion, or $158 a share. Along with $500 million in cost savings, the move will push Valeant into the high-growth market of gastrointestinal drugs. The Health Care SPDR ETF (XLV added 0.19%.

Apple (AAPL hit a new record high after climbing 2.1% to $132.23. The world's largest company said it would make its largest European investment by building two data centers in Ireland and Denmark. The project is expected to cost 1.7 billion euros ($1.9 billion).

Discovery Communications (DISCA was among the best performers, rallying 4.4% after The Australian Financial Review reported 21st Century Fox (FOXA was interested in a takeover. A Fox spokesperson has since refuted the report. 

Boeing (BA shares were 2.4% lower after Goldman Sachs downgraded the aerospace company to "sell" from "neutral." Analysts said after nearly a decade of undersupplying the market, Boeing and Airbus have caught up with demand which may hinder growth.

Federal Reserve Chair Janet Yellen will give her semi-annual monetary policy testimony to Congress on Tuesday and Wednesday. Investors will watch closely for any hints from Yellen of a rate hike time-line. Though Fed minutes released last week suggested a more dovish turn for the central bank, Wall Street will dissect Yellen's remarks to determine whether a June hike is still in the mix.

"Fed Chair Janet Yellen's ... [will offer] traders a new perspective from the Fed in the wake of the strong January jobs report, which saw payrolls expand by over 1 million jobs over the past three months alone," said Christopher Vecchio, currency analyst at DailyFX.

Homebuilder stocks were under pressure after existing home sales hit a nine-month low. Toll Brothers (TOL , D.R. Horton (DHI , PulteGroup (PHM and KB Home (KBH were all lower, while the SPDR S&P Homebuilders ETF (XHB slipped 0.38%.

U.S. home resales slid 4.9% to 4.82 million units in January, according to the National Association of Realtors, the lowest level since April 2014. The housing market continued to look sluggish as tight supply limited sales, kept prices high and prevented first home-buyers from entering the market.

"The general tone of this report was weak and it adds a wide array of housing indicators that have been pointing in the wrong direction, underscoring continued sluggishness in this crucial segment of the economy," said TD Securities' Millan Mulraine. "With labor market activity still buoyant and buying conditions remaining very attractive, we expect the housing recovery to regain some positive momentum in the coming months."

Moody's joined Standard & Poor's in downgrading Russia's status after continued infighting in Ukraine flouted a cease-fire agreement, increasing the likelihood of fresh sanctions from the U.S. and U.K. Companies based in Russia or that have large operations in the country fell on Monday, including search engine Yandex (YNDX , payments service Qiwi (QIWI , and telecoms VimpelCom (VIP and Mobile TeleSystems (MBT .

3M (MMM agreed to purchase Polypore International's (PPO separations media business for $1 billion, the company said Monday. In a separate deal, Japanese chemical producer Asahi Kasei said it would purchase Polypore's energy storage division. Polypore shares were up 12.8%.

HSBC (HSBC tumbled 4.7% after reporting annual profit fell 17% to $18.7 billion, below analysts' estimates for $21 billion in earnings. The bank has been hit with a number of costly fines and settlements and recently came under investigation for tax evasion at its Swiss branch.

-- Written by Keris Alison Lahiff in New York.