Photo: Reuters/Lucy Nicholson

While the energy sector is still expected to be the largest earnings growth contributor for the S&P 500 as a whole, it is seeing significant downturn, reports FactSet.

Both Exxon Mobil and Chevron are set to report earnings on Friday, which are expected to fall below estimates from June 30.

Nearly 75% of S&P 500 energy sector firms have recorded decline in Q2 EPS estimates since June 30. The sector-wide earnings growth rate has fallen to 332.1% from 390.5% at the end of Q2, the largest drop of any sector.