U.S. stocks sank in another dizzying day of trading Thursday after U.S. President Donald Trump promised stiff tariffs on imported steel and aluminum, worrying investors about possible retaliation by other countries. The Dow Jones industrial average fell 420.22 points, or 1.68 percent, to 24,608.98, the S&P 500 lost 36.16 points, or 1.33 percent, to 2,677.67 and the Nasdaq Composite dropped 92.45 points, or 1.27 percent, to 7,180.56. Trump said his administration would impose a 25 percent tariff on steel imports and a 10 percent tariff on aluminum. The news took Wall Street by surprise and caused concerns in the markets for companies that rely on aluminum and steel. Shares of Boeing fell 3.5 percent, General Motors dipped 4 percent and Ford dropped by 3 percent. Large technology companies also suffered, including Apple and Google-parent…