The next US presidential election will be held Tuesday Nov. 8 2016, and the results very likely known that evening.

We can model stock prices on the morning of Nov. 8 as a probability-weighted average of the stock values conditioned on Clinton's being elected and on Trump's being elected. After the probabilities collapse to 0 and 1 or 1 and 0, the stock prices should adjust accordingly.

In a previous question it's been noted that even 2.5% changes in the stock market are rare; but a comment under that question predicted that one would occur shortly after this upcoming election.

Will the S&P 500 change by > 2.5% from its opening on Nov. 8 to its closing on Nov. 9?

A sister question will ask about whether the change will be up or down.