U.S. stock index futures slipped slightly lower Tuesday as investors warily awaited more details out of the ongoing trade talks between the U.S. and China in London.

At 05:20 ET (09:20 GMT), Dow Jones Futures fell 75 points, or 0.2%, S&P 500 Futures slipped 7 points, or 0.1%, and Nasdaq 100 Futures dropped 28 points, or 0.1%.

Those moves follow a muted day on Wall Street as investors kept an eye on a day of trade talks between officials from the two largest economies in the world, with the discussions continuing into a second day.

The benchmark S&P 500 eked out a slight gain in the previous session, its second winning day in a row, fueled by advances in shares in tech giants Amazon (NASDAQ:AMZN) and Google-parent Alphabet (NASDAQ:GOOGL).