On Thursday, the Dow capped a three-day surge so strong it lifted the index out of a short-lived bear market. The good vibes ended quickly Friday morning at the opening bell, with the Dow falling more than 1,000 points, or more than 4.5%. Both the benchmark S&P 500 and the Nasdaq slid by similar percentages. "Bear market 'head-fake' rallies are not uncommon," Maneesh Deshpande of Barclay's tells CNBC. Big uncertainties such as how long quarantines will have to last amid the coronavirus outbreak continue to weigh on investors, he added. The Wall Street Journal notes that the closely watched Cboe Volatility Index is back up near historic highs. European stocks also fell, though Asian stocks were generally higher. (More stock market stories.)