Sometimes the market's risk-off switch flips so hard you can hear it click. Tuesday was one of those days. President Donald Trump renewed his tariff threats – this time tied to Greenland, of all places – and investors responded by dumping everything that wasn't nailed down.

The S&P 500 and Nasdaq 100 both dropped around 2%, marking their worst sessions in over three months. But the real carnage hit the so-called Magnificent Seven tech stocks, which collectively shed roughly $700 billion in market value. That's not a typo. Seven hundred billion dollars, gone.

Nvidia Corp. (NVDA) and Apple Inc. (AAPL) led the selloff, each losing more than $170 billion in market cap.

Gold Surges As Investors Flee to Safety

While stocks cratered, precious metals did what they're supposed to do when things get weird: they rallied hard. Gold – tracked by the SPDR Gold Shares (NYSE:GLD) – jumped 1.9% to $4,760 per ounce, notching fresh all-time highs as investors scrambled to reprice geopolitical and trade risks.

Nigel Green, CEO of deVere Group, says the violent rotation into safe-haven assets signals something important: markets are starting to believe Trump might actually follow through on his threats.

"Markets are now behaving as if this is no longer political theatre," Green said. "The surge in gold and the sharp repricing of risk assets suggest investors believe the probability of U.S. action on Greenland has risen materially."

The Economic Cost of a Real Trade War

Here's where things get more serious. Economists are warning that if this escalates into a genuine transatlantic trade conflict, the economic fallout could be substantial.

Oxford Economics ran the numbers: if the U.S. slaps an additional 25% tariff on European countries and Europe retaliates in kind, U.S. GDP would be about 1% lower than baseline at peak impact.

"The peak hit to the euro area would be similar but more drawn out, while the inflationary impact would be only modestly positive," said Ben May, director of global macro research, and Rory Fennessy, senior economist, in a report released Tuesday.

And because the U.S. and European economies are massive, Oxford Economics cautioned that the damage wouldn't stay contained. Under this scenario, global GDP growth could slow to around 2.6% – below the 2.8% to 2.9% range seen in recent years and the weakest pace since 2009, excluding the pandemic year.

Even Treasuries Aren't Working

Here's the weird part: U.S. Treasuries, which usually catch a bid when stocks get hammered, failed to provide their typical safe-haven support. Yields actually kept rising, pushing bond prices lower even as equities sold off.

Adam Turnquist, chief technical strategist at LPL Financial, pointed to several culprits driving yields higher.

"Rising deficits, escalating tariff threats and geopolitical tensions – combined with growing concerns over Federal Reserve independence – have pushed Treasury yields higher this year," he said in an emailed note. "Rising global yields, particularly in Japan, have also reduced the relative appeal of U.S. Treasuries."

When your usual safe havens stop working the way they're supposed to, that's when markets get truly uncomfortable. And Tuesday was definitely one of those days.