U.S.-based independent power producer (IPP) Calpine Corp.'s performance has been stronger than our previous forecasts, and it has improved its adjusted debt to EBITDA ratio to below 5.0x. S&P Global Ratings has upgraded Calpine to 'BB-' from 'B+'. We have also raised our ratings on Calpine's senior secured debt to 'BB+' from 'BB', and its senior unsecured debt to 'B+' from 'B'. The recovery ratings on the secured and unsecured debt are unchanged at '1' and '5', respectively. We have revised Calpine's financial risk assessment to FS-5 from FS-6, to reflect our expectation that adjusted leverage will be below 5.0x and sponsors would reassess capital allocations to maintain that ratio below 5.0x. The stable outlook reflects our expectation that adjusted