No president in modern history has followed the stock market more obsessively as a barometer of success than Donald Trump. You can see it in the dozens of tweets he’s sent referencing the Dow Jones Industrial Average, in the way every record is celebrated while lurches are pinned on the Democrats.

Now, new academic research finds that the market has a measurable influence on how people who own shares vote — potentially a big one. The study, which compared electoral preferences with levels of dividend income, suggests that had stocks rallied instead of plunging in 2008, John McCain may have won key states like Florida and Ohio.

“The benefit of looking to the stock market as a prediction is, it gets away from the emotional aspect of what a particular candidate is offering,” Michael Ball, Managing Director of Denver-based Weatherstone Capital Management Inc., said by phone. “You have basically investors putting their money where the mouth is in terms of the economic reality.”