Independent power producer Dynegy 's ( DYN ) $6.25 billion purchase agreement for Midwest power plant assets got a thumbs up from investors, who drove its shares up sharply Friday. Dynegy will acquire 12,500 megawatts of coal and natural gas generation capacity from Duke Energy ( DUK ) and Energy Capital Partners, nearly doubling its existing energy portfolio to 26,000 MW. Dynegy shares were up about 9% on the stock market today. Duke fell less than 1%. The deal came after Duke, the largest electric power holding company in the U.S., said in mid-February that it intended to exit its Midwest commercial generation business. Dynegy, which serves parts of Illinois, Pennsylvania, California, Nevada, New York and Massachusetts, will pay $2.8 billion for Duke's assets and $3.45 billion for ECP's assets. The transactions are expected to close in early 2015. Houston-based Dynegy, which finished its exit from bankruptcy in November 2013 as a smaller, leaner company, expects cost reductions of $40 million a year.