This is what you must know before the bell:

1. The Dow Jones Industrial Average rose 0.58% on Tuesday to close at 20,743, capping off its eighth straight day of gains following a better-than-expected quarter from Walmart (WMT - Get Report) .

2. Luxury homebuilder Toll Brothers (TOL - Get Report)  posted fiscal first-quarter earnings of 42 cents a share, topping analysts' forecasts of 35 cents.

3. Shares of Bristol-Myers (BMY - Get Report)  were rising close to 1% in premarket trading Wednesday after billionaire activist investor Carl Icahn took a stake in the drug giant.

4. Facebook (FB - Get Report)  is in talks with Major League Baseball to live stream one game a week during the upcoming season.

5. Oil giant Saudi Aramco asked JPMorgan Chase (JPM - Get Report)  and Morgan Stanley (MS - Get Report)  to assist with its upcoming initial public offering and could call on another bank with access to Chinese investors.