When U.S. stocks were flying high in 2017, “Trump trade” became one of Wall Street’s favorite buzzwords, shorthand for the optimism that the president and a Republican-led Congress would deliver outsize economic growth and energize an aging bull market.

For a while, the bet paid off — handsomely. The president’s appointees worked to loosen regulations on banking, Internet services, and air pollution, and in December, Trump signed a tax cut that reduced the top corporate rate to 21 percent from 35 percent. Fevered speculation about the Dow Jones Industrial Average reaching a record high of 21,000 in early 2017 gave way to anticipation of even higher milestones; the blue-chip index topped 26,000 this January and started churning toward 27,000.