Stocks gain for third day; longest win streak of 2015

"U.S. stocks advanced on Wednesday, with Wall Street's volatility unabated, as investors largely adopted the view that the European Central Bank would implement a large-scale bond-purchasing program."

- UnitedHealth Group rose after posting a better-than-expected fourth-quarter profit;
- International Business Machines fell after the Dow component offered a tepid outlook;
- Netflix gained after the supplier of streaming videos reported earnings that beat estimates.

Multiple news outlets quoted sources in reporting the ECB's executive board had proposed monthly bond purchases of roughly 50 billion euros in a quantitative easing program that would last at least a year.

"That gets you to 600 billion euros, which is north of expectations, so if in fact the source is credible that's enough to have markets reacting positively; buy the rumor and sell the news,"

Read more: For every three shares falling, roughly five rose on the New York Stock Exchange