The 2016 presidential election surprise triggered a large, positive stock market response on 9 November, strongly contradicting pre-election assessments of how the market would react if Trump won. Moreover, equity returns varied enormously across firms one, two, and three days after this event. We show that policy risk exposures calculated from the text in Part 1A of 10-K filings explain much of the cross-firm differences in Nov 9 equity returns. Firms with high exposures to generic regulation, labor regulation, food and drug regulation, financial regulation, intellectual property policy, government purchases, and brown-energy regulations had relatively high equity returns. On the other hand, firms with high exposures to healthcare policy risks, business tax credits, taxation of foreign profits, sales and excise taxes, subsidies, and green-energy regulation performed relatively poorly. The stock market did not fully digest the implications of the election outcome by market close on 9 November. Instead, (conditional) firm-level returns over Days 2 and 3 after the election strongly reinforced the initial market response to the election surprise on Day 1. These results suggest that equity prices do not immediately and fully adjust to surprise events that (i) involve unusual shifts in the structure of price-relevant risks and (ii) require large information processing resources to fully assess. This is at odds with the Efficient Markets Hypothesis, which says that stock prices quickly adjust to publicly available information.