Constellation Energy Corporation ( CEG, Financials) said Friday that it will purchase Calpine Corporation ( CPN, Financials) for $26.6 billion in cash and shares, becoming the largest US renewable energy provider. The agreement combines Calpine's low-carbon natural gas and geothermal with Constellation's emissions-free nuclear.

In interesting timing, Friday's announcement came on the silver anniversary of the disastrous AOL/Time Warner merger.

US energy giant Constellation Energy has agreed to acquire Calpine Corporation, an independent power producer, for $26.6 billion, including debt considerations. The transaction includes 50 million shares of Constellation stock, $4.5 billion in cash, and the assumption of about $12.7 billion in Calpine’s net debt.