NEW YORK (AP) -- Shares of companies that drill for natural gas rose Wednesday as an analyst said prices could keep rising and natural gas futures reached their highest prices in two and a half years.

Citi Investment Research analyst Anthony Yuen said U.S. prices for natural gas could keep rising because the harsh winter weather will lead to sustained strong demand, depleting inventories. He said prices could reach $5 per million BTUs, a threshold they did not break last winter.

In afternoon trading the biggest gainers were Southwestern Energy Co., which advanced $1.77, or 4.4%, to $42.09, and Range Resources Corp., which picked up $2.31, or 2.7%, to $87.24. Cabot Oil & Gas Corp. shares rose $0.80, or 2.1%, to $39.89 and Chesapeake Energy Corp. shares ticked up $0.48, or 1.8%, to $26.93.

Earlier in the day shares of Range Resources hit an all-time high of $88.24 and Cabot also reached an all-time high at $40.62. Southwestern shares set a two-year high of $42.06.

Elsewhere in the sector Devon Energy Corp. stock gained $0.66 to $60.34 while Clayton Williams Energy shares added $1.14 to $72.03 and shares of QEP Resources edged up $0.27 to $31.07.

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