Energy stocks fall as oil slips below $80

Goldman Sachs analysts now expect U.S. oil prices to be roughly $75 a barrel in 2015, down from their previous forecast of $90 a barrel. Goldman also sees Brent crude, a benchmark used to price international oils used by many U.S. refineries, to be around $85 a barrel.

Rising oil production, particularly in the U.S., and the concerns about weaker economic growth internationally, has soured investors on the prospect for crude oil and the companies that produce it.

Goldman Sachs is the latest Wall Street bank to lower its forecast for crude prices, saying that OPEC was unlikely to reduce exports in an effort to lift prices and that U.S. production continues to expand. The bank sees oil stabilizing at $80 a barrel until at least 2017.

Energy stocks were hit hard following Goldman's report, particularly the energy exploration and services companies. Halliburton, Nabors Industries, Newfield Exploration and Schlumberger were all down 4 percent or more. The S&P 500 energy sector was down 2.5 percent Monday, far more than the 0.2 percent decline in the overall market.

Benchmark U.S. crude was down 37 cents to $80.65 a barrel Monday afternoon after falling as low as $79.44. Brent crude was down 70 cents to $86.13.