** Shares of U.S.-based independent power producers rise between 1% and 5% in thin premarket trading

** Constellation Energy CEG.O up 1.9% at $347.31, Vistra VST.N rises 2.3% to $163.64 and Talen Energy TLN.O up 5.1% at $369.99

** The largest grid operator in the U.S., PJM Interconnection, reported fresh record-high capacity prices of $333.44 a megawatt-day in its auction on Wednesday

** PJM holds such auctions to determine the prices that energy companies are paid to guarantee they run their power plants when called upon

** Melius Research analyst James West says CEG and TLN are more exposed to PJM, with 49% and 98% of generation, respectively

** As of last close, CEG has gained 52.4%, VST is up 16% and TLN is up 74.7% this year

(Reporting by Vallari Srivastava in Bengaluru)

((Srivastava.Vallari@thomsonreuters.com;))