President Trump, on Oct. 19, 2017. (Jabin Botsford/The Washington Post)

President Trump once again took to Twitter to brag about his favorite success metric: The still-climbing stock market.

We’ve noted before that the Dow Jones industrial average has been on a tear, continuing a bull market that began in 2009. In March, the increase in the Dow Jones since Election Day was historically large; since then, though, it’s slipped down into “better than most” territory.

For Trump, though, it’s seen as a constant thermometer of his success, worth citing regularly (34 times since his inauguration) as evidence of how well his economic policies are doing and how much the American people have benefited from his presidency.

There’s just one problem. The benefits of that market surge are not only not felt by all Americans, but more than a third of the likely benefit has gone to people who aren’t American at all.

In March, former Joe Biden economic adviser Jared Bernstein outlined the nature of stock ownership in the United States. A little less than half of the country — 46 percent — owns stock, either through retirement accounts and other funds or directly. But there’s a big difference between your having 10 shares of IBM and the amount of stock that, say, Warren Buffett owns. In terms of the value of those stocks, the top 10 percent of Americans hold four times as much as the bottom 90 percent. The top 1 percent alone holds twice as much value as the bottom 90 percent. That’s where most of the benefit to an increase in stock values goes.

What’s more, new analysis from the Tax Policy Center’s Steven Rosenthal shows that more than a third of stock is held by foreign investors — either in stock portfolios or in direct investments. In the early 1980s, according to Rosenthal’s calculations, the percent of corporate stock held by foreign investors was a little over 10 percent. In 2016, the figure was 35 percent.

(Steven M. Rosenthal / Tax Policy Center)

Rosenthal’s point in analyzing the extent of foreign investment in the market was to note that they would receive a “windfall” from the tax cuts proposed by Republican leaders (the “Big Six”). From his report:

As estimated here, a lower corporate income tax rate would benefit foreign investors by $70 billion in the first year alone. All the individual and business tax cuts in the Big Six tax plan, as currently described, would benefit middle-income U.S. households (those in the 40th to 60th income percentile) by only $23 billion in the first year.

But even setting aside the issue of how tax cuts would benefit that group, Rosenthal’s analysis is a reminder that the surge in the U.S. markets benefits a lot of non-Americans. Trump likes to brag about how the markets have added more than $5 trillion since Election Day. Since Rosenthal’s analysis (using data from the Federal Reserve) looks at value, that means that Trump’s market surge may have meant a gain in value of about $1.8 trillion for foreign investors — as well as a substantial gain for wealthy Americans.

In that sense, it’s a weird metric for the populist president to champion (even if he hadn’t repeatedly disparaged the bull market as a “bubble” as a candidate). It’s also a risky metric, given the likelihood that, at some point, the markets will experience a significant correction. But it makes perfect sense given that this is Trump we’re talking about: A businessman-turned-president who’s no doubt used the markets as a guide to his performance for years.

The implication of Trump’s tweets over the short term is that the improving market helps everyday middle-class Americans. To some extent, it does. But it largely helps people who are either not middle-class or not American — or neither.