President Donald Trump takes part in a forum called Generation Next at the Eisenhower Executive Office Building in Washington, U.S., March 22, 2018.

One look at the biggest decliners in the Dow Jones industrial average over the past month reveals investors are really worried President Donald Trump's protectionist policies may spark a trade war with China.

The Dow dropped 724 points Thursday after Trump signed an executive memorandum that would impose tariffs on up to $60 billion in Chinese imports. A comeback attempt by the market last month has now failed with the average briefly dipping back into correction territory on Thursday.

Dow companies with large exports to the China are among the biggest losers over the past month due to the risk the Asian country may retaliate against American firms.

China generates more than 12 percent of Boeing's sales, according to FactSet.

The Chinese embassy released a statement late Thursday saying China "would fight to the end ... with all necessary measures."