U.S. stock index futures bounced around in volatile trading late Wednesday, but picked up steam after the Senate approved a $2 trillion coronavirus-aid bill just before midnight. Dow Jones Industrial Average futures YM00, -0.15% were up 44 points, or 0.1%, as of midnight Eastern, after swinging up and down a range of about 200 points earlier. S&P 500 ES00, -0.53% and Nasdaq-100 futures NQ00, -0.38% were about flat. Earlier Wednesday, the Dow DJIA, +2.39% logged its first back-to-back gains since February, though stocks fell toward the end of the session as a roadblock emerged concerning the $2 trillion coronavirus stimulus bill in the Senate.