Traders are looking for Calpine to rally.

optionMONSTER's monitoring program shows that about 7,200 May 15 calls were purchased for $0.50 to $0.60 on Friday. Volume was more than 5 times the open interest at the strike, indicating that new money was put to work.

Long calls lock in the price where investors can buy stock, allowing them to profit from a rally with limited capital at risk. Their cheap cost can also generate significant leverage on a percentage basis if shares move in the right direction. (See our Education section)

CPN rose 1.87 percent to $15.28 on Friday but is down 5 percent in the last three months. The next quarterly report is estimated for pre-market hours on July 28.

Overall option volume was 3 times greater than average. Calls outnumbered puts by a bullish 13-to-1 ratio.

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