Talk about a blown lead. The Dow Jones Industrial Average gave up a 352-point gain to end lower on Monday and highlighted a market that has grown increasingly unsettled amid concerns about global growth and escalating tariff clashes between the U.S. and China.

The action marked the biggest U-turn for the Dow industrials DJIA, -0.99%  since Feb. 7, when the Dow erased a roughly 382-point gain to finish with gut-wrenching losses. On Monday, the Dow closed down 245 points, or 1%, at 24,442.92. The day’s losses were even more stomach churning than that closing level implies because the blue-chip gauge earlier had been down by as many as 566.08 points to an intra-session low of 24,122.23, which would have put the Dow in correction territory for the second time in 2018. Corrections are usually defined by a drop of at least 10% from a recent peak. (The S&P 500 index SPX, -0.66% already is in correction territory after last week’s ugly action.)

Losses accelerated late-Monday after a Bloomberg News report surfaced indicating that President Trump’s administration was prepared to impose tariffs on all China’s imports, ramping up a tit-for-tat spat between the world’s biggest economic superpowers that has been at the heart of the recent downturn, market participants say. Industrial giant and Dow component Boeing Co. BA, -6.59%  led the 122-year-old stock index’s losses, contributing a whopping 163 points to the price-weighted Dow’s decline. Boeing’s shares declined $23.68 or 6.6%, and is the Dow’s most influential component by dint of its $335.59 price. The stock is set to drop by almost 10% this year.