There is one clear and present danger for stocks in the week ahead: the first presidential debate on Monday, September 26 (9 pm EST). Hillary and Donald will face off in an event that rivals the hoopla around Ali and Frazier. Many experts expect TV ratings to top the all-time high of the 2015 Super Bowl, which had 114 million viewers. With Trump now virtually tied with Clinton in many national polls and even ahead in several key battleground states, the fallout on stock prices from the debates could be profound.

Here’s how professional investors are handicapping the binary outcomes from this event: If Trump is the definitive winner of the debate, there could be financial bedlam the next day.

That is not a statement of political preference. The fact is that investors abhor uncertainty, and The Donald brings an almost unprecedented supply of incertitude to the table if elected. Not only does he not have a political history upon which to base an expectation of his future presidential decisions, but the man is known for publicly switching positions on a subject within a single sentence.

Also, many (on both the left and right) consider the potential for global geopolitical turmoil with a Trump presidency to be high, since one of Trump’s main appeals to his supporters is his contempt for other nations and making America “strong again.” During the Republican primaries, he even boasted, “I love war, in a certain way.” Even if Trump is not a trigger-happy Commander-in-Chief, the increased possibility of that risk will bring uncertainty to markets.

On the other hand, Clinton is considered to be a known commodity and “more of the same old politics” by her detractors. After all, she has been in the public eye for a quarter of a century. For these reasons, it is likely that investor uncertainty associated with a Clinton presidency is quite low, and stocks will not be any more affected by a Clinton presidency than any other presidency (except Trump).

Because of the unprecedented TV viewership expected and the potential for virtually anything to happen, the Sept. 26 debate will be an event that many experts believe will determine the outcome of November’s election. While many voters have already made their decision, many others have not and Monday night’s debate will be critical for the two candidates.

With voters having low expectations for him, many experts say that all Trump needs to do to win the debate is to keep his head on his shoulders and act “semi-presidential.” On the other hand, Clinton is a policy wonk and knows the government inside and out. Compared to Trump, voters standards for her presentation are quite high.

An enormous number of investors, both professional and nonprofessional, will pay close attention to the debate and will use the Tuesday’s market open to begin discounting the future certainty/uncertainty of a Clinton/Trump presidency. On a fundamental basis, stocks are extremely overvalued; the S&P 500 is at its second highest, non-recession P/E level since its creation. Also, as discussed above, stocks are at a critical technical tipping point. With a “Bearish Rising Wedge” above and “Triple Bullish Support” below, the tension is palpable.

Should Trump clearly win the debate, we could see a significant sell-off beginning on Tuesday. Depending on how long this selloff continues, it might provide a distinct opportunity to purchase stocks at a discount, which is our specialty. Should Clinton clearly win the debate, we may see a powerful relief rally. There may have never been a more important TV event in the history of America than Monday night’s debate. In many ways, the future of America depends on it – and the near-term future of the stocks might also.