NEW YORK ( TheStreet) -- Stocks turned negative on Thursday, after posting gains earlier in the session. Health care stocks surged on the heels of a Supreme Court ruling, while shares of Humana (HUM) - Get Report jumped after reports surfaced that Aetna (AET) was close to acquiring the health care giant.

The S&P 500 lost 0.20%, the Dow Jones Industrial Average fell 0.31%, and the Nasdaq gave up 0.23%.

Bloomberg reported Aetna was closing in on an acquisition of Humana and could reach a deal as early as this weekend. Humana shares rose almost 7% after being halted earlier for volatility.

Meanwhile, health care stocks such as Aetnaand UnitedHealth (UNH) - Get Report gained following the 6-3 Supreme Court ruling that determined subsidies should be available in states where health care exchanges weren't created. Hospital operators also rose sharply; HCA (HCA) - Get Report jumped 8%, while Tenet Healthcare (THC) - Get Report rose almost 13%, making it the best-performing stock in the S&P 500. Community Health (CYH) - Get Report added 12%.

"Health care is no longer a defensive sector, it's a growth sector," Mary Ann Bartels, chief investment officer of portfolio solutions at Merrill Lynch Wealth Management, told TheStreet TV. "We have 10,000 baby boomers turning 65 who will need health care going into retirement. [The Supreme Court ruling] is another positive point for the health care sector."

Crude oil slipped below $60 a barrel, falling more than 0.9% to $59.74.

Greek's leaders and the country's creditors met in Brussels on Thursday. After a three-hour meeting, no deal was reached, according to The Guardian. Greece's latest debt payment is due to the International Monetary Fund on June 30. Greece is reluctant to agree to austerity measures.

"The closer we get to the June 30 deadline it is becoming increasingly apparent that Greece will not be repaying the IMF its 1.5 billion euros on time," said Michael Hewson, chief market analyst at the London-based CMC Markets.

Personal income in the U.S. in May rose 0.5%, according to the Bureau of Economic Analysis. Consumer spending rose 0.9%, the largest jump in some six years.

Weekly jobless claims in the U.S. rose to 271,000, compared with economists' estimates of 273,000.

CenturyLink (CTL) - Get Report was the worst performing stock in the S&P 500, after analysts at JPMorgan downgraded the stock to "neutral" from "overweight," following the company's analyst day.

Barnes & Noble (BKS) - Get Report
reported a fiscal fourth-quarter loss of 37 cents a share, compared to estimates of 33 cents. Revenue came in at $1.2 billion, ahead of estimates of $1.18 billion. Shares slipped about 1.3% on the news.

Walt Disney (DIS) - Get Reportmoved higher by about 1% after announcing plans to raise its dividend 15%. The entertainment company will also make semi-annual payments to shareholders, instead of annual ones.

IAC/InterActiveCorp (IACI) announced plans for an initial public offering of its popular dating Web site, pushing shares higher by 4%.

Accenture (ACN) - Get Reportreported earnings per share of $1.30, eclipsing Wall Street's estimates of $1.23. The consulting firm also raised its revenue outlook for the year and expects sales to rise 9% to 10%, compared to a previously reported 8% to 10%. Shares gained 2%.

Nike (NKE) - Get Reportreports quarterly earnings after the closing bell on Thursday and Wall Street is looking for profit of 83 cents a share.