NEW YORK (AP) ¿ Exposure to natural gas prices, debt levels and changing stock prices prompted a Jefferies & Co. analyst to raise his ratings on two electric utilities on Monday while lowering it on a third. Analyst Paul Fremont upgraded Calpine Corp. to "Hold" from "Underperform," citing its stock price and its reduced exposure to natural gas. The power producer, which is based in San Jose, Calif., has been trading at a 10 percent premium to its peers, but Fremont believes this heightened value is warranted due to the company's long-term sales contracts which have mitigated exposure to fluctuations in commodity prices. Fremont reaffirmed his 2009 earnings estimate of 35 cents per share and raised his 2010 estimate by 5 cents to 25 cents per share. Analysts polled by Thomson Reuters expect 2009 and 2010 profits of 29 cents per share and 30 cents per share, respectively. Shares of Calpine rose 43 cents, or 3.9 percent, to $11.43 in morning trading. Fremont raised his rating on Dynegy Inc. to "Hold" from "Underperform." He said its shares have reached a fair value. He also noted Dynegy, based in Houston, recently retired $420 million of notes due 2011, which he said should lower interest expense. He raised his 2010 profit estimate by 5 cents to 15 cents per share. Analysts expect a 2010 loss of 21 cents per share.