US futures post gains as investors await tax vote By: CNBC.com News December 19, 2017 at 05:00 AM EST U.S. stock index futures are set for a positive open Tuesday, as investors get ready for a vote on a bill that would slash taxes for corporations. Read More >> Related Stocks: Dow Industrials SPDR PowerShares QQQ S&P 500 Ishares Core ETF SPDR S&P 500 ETF Trust