S&P 500 companies are on track for their first year-over-year earnings decline since 2009, led by energy woes and a sluggish global economy, with weak revenue a continued concern. With 341 companies already reporting, the large-cap S&P 500's earnings are seen falling 1% as revenue declines 3.6%. Earnings haven't dropped since Q3 2009, but it would be the third straight decline for sales.