It was a rough day on Wall Street Thursday, as all three major indices closed lower, after posting gains earlier in the trading session. The Dow Jones Transportation Index entered correction territory, which sent jitters throughout the markets. Meanwhile, investors still remain worried about Greece's debt woes. Talks are set to resume on Saturday, just days ahead of June 30th, when Greece's next payment to the IMF is due. And it was a huge day for health stocks. Shares of Humana (HUM) closed up TKTK percent, following a Bloomberg report saying the health insurance giant was close to being acquired by Aetna (AET). But the rally also extended to hospital operators like Tenet Healthcare (THC), HCA (HCA) and Community Health (CYH), which came on the back of the Supreme Court's ruling in favor of Obamacare's Federal Subsidies. Plus, crude oil slipped below $60 per barrel, settling at 59.66, a decline of 1%.