The stock market may soon get much-needed support from a surprising source: U.S. President-elect Donald Trump’s low popularity rating.

That’s because there is an inverse relationship between presidential approval ratings and the stock market, according to an analysis conducted by Ned Davis Research. Donald Trump’s approval rating leading up to Inauguration Day on Jan. 20 is lower than it has been for every president except one in the post-World War II period.

The other president joining Trump with low approval ratings going into office? Donald Trump — as he began his first term in January 2017.

The data from the Ned Davis analysis are plotted in the chart below. During weeks in which the president’s approval rating was above 65%, for example, the Dow Jones Industrial Average’s DJIA return was 2.4% annualized, on average. The Dow did much better when the approval rating was between 50% and 65% (7.6% annualized, on average) and better still when the approval rating was lower, between 35% and 50% (10.4% annualized, on average) — like Trump is now.

There’s one major exception to this inverse correlation: When a president’s approval rating is particularly low — below 35% — the stock market tends to perform especially poorly. This has happened rarely — in just 6.8% of the weeks since 1959, according to Ned Davis Research. Examples are the weeks just prior to Richard Nixon’s resignation in 1974, and the 2008 financial crisis near the end of George W. Bush’s second term.

Trump’s current approval rating — 47.2% — is well above this danger zone, and right in the middle of the sweet spot for approval ratings associated with above-average stock-market returns. President Joe Biden’s approval rating, in contrast, has hovered over the past couple of months barely above the danger zone — currently at 39% .

As you can see from the chart above, no post-World War II’s president’s approval rating was in the below-35% danger zone on their Inauguration Day. Yet as I discussed in a column last fall , the typical pattern is for a president’s approval rating to drop in the weeks following Inauguration Day, as the honeymoon inevitably wears off.