Wall Street’s summertime slump continued as dramatic protests in Hong Kong dimmed hopes that the US will come to a trading truce with China.

The Dow Jones industrial average fell 391.00 points — or 1.5% — Monday, with losses accelerating late in the session, to close at 25,896.44.

Monday’s Dow dip followed news that Hong Kong’s airport was shut down after pro-democracy protesters flooded the main terminal. Adding to investors’ jitters, mainland China officials likened the protests to “terrorism,” and riot police fired tear gas into a subway station in a violent crackdown.

“Putting the hammer down on Hong Kong would belie the image Beijing is portraying in the trade talks,” explained Jack Ablin, chief investment officer at Cresset Capital Management.

The S&P 500 and Nasdaq were both off 1.2%.

Further dashing hopes that a trade deal will be reached anytime soon, Goldman Sachs analysts predicted that a deal “will not be reached” before the presidential election next year.

In April, the market assumed an 80% chance of a trade agreement, according to the investment bank. That figure now stands at 13%.

Trade-sensitive stocks such as Caterpillar and Boeing closed down 2.2% and 1.4%, respectively, in Monday’s session. But it’s not just trade woes that have investors on edge, said Peter Cardillo, chief market economist at Spartan Capital Securities.

“Mainland China is beginning to become more vocal, which is sending fears that it could disrupt global business,” Cardillo told The Post.

Investors on Monday continued plowing into so-called safe-haven assets such as gold and government bonds. The flight to safety sent the yield on the 10-year Treasury note lower, intensifying fears that a slowdown is coming. Bond yields move in the opposite direction to price.

“We’re probably heading for yield levels last seen during the financial crisis,” Cardillo said.

Financial stocks were hit by the drop in bond yields on fears of falling profits.

Goldman Sachs’ shares fell 2.9%, while Bank of America and JPMorgan Chase were down 2.5% and 2%, respectively.