It was a volatile end to the week after federal investigators reopened a case into Hillary Clinton's email server. The FBI had found emails pertinent to the case, though did not know whether the material would be significant. Stocks plummeted before rebounding. Crude oil ended with a weekly loss for the first time since mid-September on skepticism over an OPEC deal. Oil held lower despite the first weekly decline in active drilling rigs in the U.S. since June. Regeneron (REGN) - Get Report fell after the FDA delayed approval for its treatment for rheumatoid arthritis. Officials ruled on a delay after finding manufacturing deficiencies at partner Sanofi's (SNY) - Get Report facility. Hanesbrands (HBI) - Get Report surged after providing positive sales guidance for its fourth quarter. The apparel brand anticipates quarterly sales of at least $1.7 billion. That came in above consensus. TheStreet's Keris Lahiff reports from Wall Street.