Mirant on Monday withdrew its near $8bn bid for rival NRG after investors threatened to take action against the power producer’s board while Jana Partners made a $1.8bn offer for Houston Exploration.

Pirate Capital, one of four hedge funds that objected to Mirant’s hostile takeover of NRG, said it would move for control of Mirant’s board unless Mirant withdrew its bid by Wednesday and put itself up for sale.