Over the past year, adjusted earnings calculations for S&P 500 companies have been an average of 30 percent higher than what GAAP calculations say, according to Reuters. This is the biggest difference between the two measures since 2008, and the third highest since 1994. The gulf could indicate that the the last year's already-weak earnings figures--a 2.9 percent decline over 12 months--could be even worse than first thought, said Reuters. The sectors with the biggest difference between adjusted earnings and GAAP numbers are the energy, materials and healthcare, said Reuters. 

Most companies now report earnings on an adjusted basis, according to The Business Insider: 87 percent. This represents a seven percent growth since 2014. SEC Chair Mary Jo White recently expressed concern about this trend and hinted that the commission might seek to regulate the use of adjusted earnings figures, according to The Wall Street Journal. She said companies like using them because, through excluding items like tax increases and one-time costs, adjusted earnings figures look better. White warned, though, that these numbers can confuse investors about the true financial health of a company.