US futures fluctuate as political turmoil keeps investors on edge By: CNBC.com News September 25, 2018 at 05:19 AM EDT U.S. stock index futures eked out minor gains ahead of Tuesday's open. Read More >> Related Stocks: Dow Industrials SPDR Nasdaq ETF S&P 500 Ishares Core ETF SPDR S&P 500 ETF Trust