President Trump signed an executive order on health care at the White House on Thursday.

It is unlike President Trump to cheer when stocks fall, but early on Saturday he did just that.

“Health insurance stocks, which have gone through the roof during the ObamaCare years, plunged yesterday after I ended their Dems windfall!” he tweeted.

On Thursday, the administration announced it would stop paying subsidies to health insurance companies that help cover costs for low-income people.

“That money is a subsidy for insurance companies,” Mr. Trump said on Friday. “Take a look at their stocks. Look where they are. They’re going through the roof.”

In another tweet on Saturday, Mr. Trump said he was “very proud” of an executive order he had signed Thursday. The order sought to increase competition among insurers, in large part by encouraging associations…