2018.05.3118:37:00UTC+00U.S. Stocks Slide on Fresh Trade-War Concerns but Notches Monthly Gains

U.S. equities edged down on Thursday after the Trump administration announced it will impose tariffs on metal imports from Canada, Mexico and the European Union, triggering retaliatory measures from a number of its trading partners.

The Dow Jones Industrial Average declined 251.94 points, or 1.02 percent, to 24,415.84, the S&P 500 edged down 18.74 points, or 0.69 percent, to 2,705.27 and the Nasdaq Composite lost 20.34 points, or 0.27 percent, to 7,442.12.

Despite the days declines, the S&P 500, Dow Industrials and Nasdaq recorded their biggest monthly percentages gains since January. The small-cap Russell 2000 index, notched its largest monthly percentage increase since September. Utilities, perceived as a defensive sector, were the biggest gainers among the S&P 500's major sector indexes, rising 0.1 percent.

For the month, the S&P increased 2.16 percent, the Dow rose 1.05 percent and the Nasdaq advanced 5.32 percent. The S&P 500 posted 19 new 52-week highs and 10 new lows; the Nasdaq Composite recorded 144 new highs and 49 new lows.

U.S. Commerce Secretary Wilbur Ross said a 25 percent duty on steel imports and a 10 percent levy on aluminum imports from its allies would be effective beginning Friday.

U.S. allies retaliated immediately. Mexico responded by imposing measures on U.S. farm and industrial products. Meanwhile, Canada said it will impose retaliatory tariffs on $12.8 billion worth of U.S. exports and challenge the tariffs under the NAFTA deal and the WTO.

Adding to trade concerns was a report that the U.S. was looking to target German automakers, after starting a probe in the previous week into car and truck imports.