S&P Global Ratings today affirmed its 'B+' corporate credit rating on Calpine Corp. on the announcement that it is being acquired by the consortium of Energy Capital Partners (ECP) and a consortium of investors in a take-private transaction. At the same time, we affirmed our 'BB' issue-level senior secured ratings on the company. The recovery rating on Calpine's senior secured debt is '1', indicating our expectation for very high (90%-100%; rounded estimate: 95%) recovery in a hypothetical default scenario. We have affirmed our 'B' senior unsecured issue-level ratings on the company. The recovery rating on Calpine's unsecured debt is '5', indicating our expectation for modest (10%-30%; rounded estimate: 25%) recovery in a default scenario. We have also affirmed our 'BB'