Wall Street drifted modestly lower before the opening bell as uncertainty over global trade seeps into the busiest week of earnings this quarter from major corporations, as well as a raft of economic indicators Futures for the S&P 500 dropped 0.

U.S. stocks are giving back some of their big recent gains, ahead of potential flashpoints later this week that could bring more sharp swings. The S&P 500 fell 0.8% Monday