Are you prepared for the unthinkable? Is your portfolio prepared in case Donald Trump, rather than Hillary Clinton, wins the White House on Nov. 8?

Very few are. But after this weekend, they need to be.

The video footage of Hillary Clinton’s health “episode” on Sunday morning is not good. A member of the public, using a cellphone camera, filmed the former secretary of state being helped into a van by aides after apparently being overcome by heat at the 9/11 ceremony. She had left the event abruptly.

The so-called “optics” are damaging. And in the age of the internet, this clip can and will be repeated — over and over and over.

If Hillary Clinton were a 45-year-old sports enthusiast whose health was not in question, this might be a storm in a teacup. But she is 68 and the Trump campaign was already flinging around health scares (some obviously bogus).

Hillary Clinton ‘felt overheated’ and left 9/11 ceremony

The incident comes as opinion polls show the election is down to a few percentage points. And Clinton was already on the defensive, after saying Friday that Donald Trump voters divide into two groups — extremists, aka “deplorables,” and the rest.

(I’ll confess I don’t get this controversy. Her statement is so obviously true that it’s banal. Indeed, try rebutting it with a straight face. “No, hardly any of Trump’s supporters are extremists. Go to a Trump rally and you won’t see any.” Or: “Well, racists and misogynists aren’t deplorable.” Really? Critics tried to focus on Clinton’s claim that “half” of Trump’s supporters fell into each camp — but this is patently a figure of speech, like saying “half my relatives are morons, and the rest are idiots.” Only a twit thinks you mean 50% and 50%. Not that facts or logic have anything to do with this election anymore.)

Financial markets have been far too complacent about the likelihood of a Hillary Clinton victory on Election Day. It is far from a dead certainty — especially now. Betting at Predictit, the elections market, now give Trump a one-in-three chance of winning.

What would that mean for investors?

You’d better brace yourself for a lot of volatility. Markets don’t like unpleasant surprises. They hate uncertainty. And a possible Trump victory would mean both. Hillary Clinton is largely a known quantity. Trump isn’t. The outside world is hardly likely to stay calm at the news that the U.S. government, nukes and all, is being handed over to an unstable, inexperienced TV personality with a quick temper and a long line of incendiary threats. You should expect stocks, bonds, currencies and commodities to react.

A money manager I spoke to last week said if Trump looks like he’s winning, he’d bet on three things: “Gold, guns and germs — or in other words gold, defense stocks and health-care stocks.”

He figures Trump’s election would cause a dollar panic which would be good for gold (and other hard currencies, such as the Swiss franc). Trump has already vowed to essentially launch currency wars against trading partners such as China and Japan.

Defense contractors should do well: Trump has promised to raise U.S. defense spending drastically. (Note: Gun makers like Sturm, Ruger & Co. RGR, +1.88% , on the other hand, might suffer. They typically do best when their customers panic about Democrats in the White House, and rush out to stock up before the long expected “ban.”)

Meanwhile, a Trump victory would be bound to put the entire health-care industry in the spotlight, including the insurers, the major drug companies, biotechs and others. Investors have been wary of these stocks for fear that a President Clinton would try to bring down health-care costs by pressuring their high prices, costs and profit margins. It’s hard to be sure what Trump would do, but he has promised to push for massive deregulation.

The implications of a Trump victory wouldn’t end there. It could upend everything from construction stocks, thanks to Trump’s alleged “wall” with Mexico, to Moscow, where investors would hope for an end to Western sanctions. Interesting times.