Friday was brutal for investors. Stocks crashed after Trump threatened "massive" new tariffs on China in a Truth Social post.

Here's the damage:

• Dow: Down 500 points (1%)
• S&P 500: Fell 1.5%
• Nasdaq: Crushed 2.2%

Tech stocks got hit the hardest. And all three indexes are now down for the week.

What Set Trump Off:

China has been picking fights all week:

• Added new fees on American ships at their ports
• Started investigating Qualcomm for antitrust issues
• Tightened controls on rare earth exports
• Stopped buying US soybeans

Trump's response? A long, angry post threatening tariffs and maybe canceling his meeting with Xi Jinping.

Trump's Words That Moved Markets:

"Some very strange things are happening in China!" he wrote.

Then came the threat: "One of the Policies that we are calculating at this moment is a massive increase of Tariffs on Chinese products coming into the United States of America."

He admitted it would be "potentially painful" but said it would be good for the US "in the end."

Investors heard "painful" and started selling.

Why This Selloff Happened:

Tariffs mean higher prices. Higher prices hurt consumers and companies.

The fear:

• Companies that rely on Chinese goods pay more
• They pass costs to customers
• People buy less stuff
• Profits drop
• Stocks fall

Plus, tariff threats create uncertainty. Markets hate uncertainty.