The Dow Jones Industrial Average on Friday slipped below a closely watched midterm trend line as a selloff sparked by President Donald Trump's threat to impose tariffs on aluminum and steel imports, as soon as next week, intensified. The Dow tumbled 300 points, or 1.3% in early Friday trade to 24,267, ], which would put it in position to slip beneath its 100-day moving average at 24,447.83, according to FactSet data. The Dow DJIA, -2.87% on Thursday closed down more than 420 points at 24,608, while the S&P 500 index SPX, -2.17% and the Nasdaq Composite Index COMP, -1.34% also tumbled sharply lower. The Dow last broke below its 100-day MA on Feb. 9, as stock benchmarks were reeling after slipping into correction territory, typically defined as a decline of at least 10% from its recent peak on Jan. 26. The blue-chip gauge is still well above its 200-day MA at 23,077.02. Market technicians watch moving averages in order to help gauge short-term and long-term momentum in an asset.