NRG Energy, one of the S&P 500’s biggest year-to-date gainers, has volatile earnings due to its large derivatives-trading operation. Late last year, an accounting switcheroo let it start acting like ...

NRG Energy (NYSE:NRG), one of the S&P 500's biggest YTD gainers, has volatile earnings due to its large derivatives trading operation, but a change in the way it interpreted accounting rules starting ...