Donald Trump has taken the stock market to the limit. And he hasn’t even won the presidency yet.

After waves of selling on Tuesday night, stock market futures were halted early Wednesday morning after plunging 5%, as Trump was on the cusp of an unlikely victory over Hillary Clinton. Just after midnight, the Dow Jones industrial average was down 827 points. The S&P 500 was down 107 points. The technology heavy Nasdaq 100 had fallen 241 points.

Technically the market indexes can continue to trade, but so-called circuit breaker rules limit the amount stock exchanges can fall in a single after hours session to just 5%. So traders can buy, but it it become increasingly hard to sell. Trading, which had been brisk for most of the night in futures contracts, dried up.

While the markets were blocked from going further south, this could still be just the start of investors losses. Stock markets can resume their plunge when markets open on Wednesday morning. On Tuesday, Bridgewater Associates predicted that U.S. stock market could plunge over 10% if Trump were to win the presidential election. Investors had favored a Clinton presidency because that was seen as more predictable. Market do not like uncertainty. Others have put the possible market plunge at 5%-to-6%.

There is a history, though, of immediately stock market reactions to election results to quickly reverse. For example, the stock market quickly regained its losses in weeks after the Brexit vote. Trump has proposed cutting taxes on corporations and the rich. In the past that has been good for the stock market. What’s more, a Trump win would dramatically reduce the likelihood that the Federal Reserve would raise interest rates in December. That’s likely good for the stock market as well.