That got ugly fast.

U.S. stocks spent most of the day like a well-made cocktail: mixed but not too strong. The Dow Jones Industrial Average swung between small gains and losses for most of the day. But the market turned decidedly negative in the final hour of trading as losses accelerated and gainers pulled off the road altogether.

The Dow was down 345 points, or 1.4 percent, after earlier gaining 243 points. The S&P 500 clocked in a 1.7 percent loss. The tech-heavy Nasdaq Composite fell by 2.9 percent.

The S&P 500’s tech sector was the dog of the day, suffering a 3.4 percent loss, the worst of the index’s 11 major segments. The problems of Nvidia, which announced today that it was halting tests of self-driving cars, pushed that stock down 9.4 percent. Shares of Facebook fell 5.2 percent and are down 15 percent for the month. Mark Zuckerberg: call your Congressman. Or Senator. They’re calling you.

Another weight on tech: possible China tariffs. The U.S. government is set to announce what Chinese products will be subject to the $60 billion or so of new tariffs sometime real soon, according to White House spokeswoman Sarah Huckabee Sanders. While these are aimed at protecting U.S. technology from China’s predatory practices, not a few investors fear that China will respond with its own sanctions against major U.S. tech firms. If China takes aim at Apple, Google, and Netflix, that probably will be short-term bad news for their stocks.

Big bank shares also sold off. The KBW Nasdaq Bank Index of large banks fell 2.8 percent. The fingers that point accusingly were pointed at the bond market, where yields on longer-term Treasuries were falling. That’s supposedly bad for bank earnings. Bank of America’s shares fell 3.3 percent.

Shares of General Electric defied the market gravity, rising by 4.27 percent Tuesday. There was not any actual good news boosting GE’s prospects. If anything, GE could well find itself on the wrong side of China trade war. But there were lots rumors that a big investors whose name rhymes with Boring Muppet might be buying a piece of GE or at least a few shares. And on a day when there was nothing else going right, buying the rumor probably made sense. Especially if you were a few cocktails in.