CNBC " Halftime Report " trader Jon Najarian purchased shares of Community Health Systems for his model portfolio. Community Health Systems is a leading health-care company that owns or operates 197 affiliated hospitals with a total 30,000 beds. In other moves on Tuesday and Wednesday, Najarian sold his model portfolio position in Celgene in the CNBC trader competition. Here's why Najarian bought the health-care stock. Traders often see companies with high short interest as opportunities for sharp short-term rallies as hedge funds move to exit their short positions. "Short float in CYH is over 12 percent, one of the highest I've seen (in stocks with) unusual call activity in this year," Najarian wrote in an email Tuesday. Average daily options volume for the company is 2,400 contracts, but over 4,800 contracts traded with an hour to go into Tuesday's close. This type of activity is often a bullish sign, according to the trader. For all the picks and analysis for the "Halftime Report" portfolio, click here . Read More Santoli: Deja vu rally could prove sturdier this time Disclosure: Jon Najarian is personally long Community Health Systems stock and call options.
