** Shares of some U.S. utilities fall premarket

** Reuters reports governors from U.S. states will visit the White House on Friday to sign an agreement with the Trump administration intended to curb rising electricity costs

** Agreement includes price caps for two years on future auctions in the PJM grid and forcing new data center operators like Amazon AMZN.O and Google GOOGL.O to take on a greater share of the cost of expanding the grid

** Talen Energy TLN.O dips 8.6%, Constellation Energy CEG.O and Vistra VST.N down between 4.2% and 4.6%

** Analysts at Jefferies say the move is not a surprise but would be a clear negative shock to power investors

** There is "net risk to incumbent power CEG, TLN, VST, & Capital Power CPX.TO on new supply" - Jefferies

** However brokerage adds GE Vernova GEV.N, NRG Energy NRG.N, PPL Corp PPL.N, NextEra Energy NEE.N are well positioned to benefit from the agreement

(Reporting by Vallari Srivastava and Katha Kalia in Bengaluru)

((katha.kalia@thomsonreuters.com))