I've survived many "black swan" events in my career...
- Black Monday in 1987
- The 9/11 terrorist attacks
- The Great Recession
- COVID-19 causing a global pandemic
Nearly 2,000 years ago, the Roman poet Juvenal called a woman who was desirable enough to marry "a rare bird in the world, very similar to the black swan."
To Juvenal, who specialized in satirical poems, a black swan meant something that didn't exist.
In his 2001 book, Fooled by Randomness, financial author Nassim Nicholas Taleb used the same term to mean dangerous, highly improbable events.
Markets hate uncertainty... And big, unforeseen catastrophes are the stuff of nightmares for professional traders. They stay up at night worried they'll come into the office and find some upheaval has suddenly put them on the wrong side of all their trades.
But the whole concept is silly.
As I'll show, most of the events people called "unimaginable" were, in fact, completely predictable... if you knew where to look.
Consider the tech bubble of the late 1990s... Analysts were telling their customers to invest in "great" new companies, while sending internal memos about how crappy the businesses really were.
Wall Street made billions of dollars on corporate financing for tech companies, even as Main Street investors got burned in the eventual dot-com implosion.
Or what about the housing crisis of the late 2000s... The government and Wall Street colluded to promise people that they could get a house at nearly any price and without taking much responsibility.
Then, Wall Street packaged the mortgages into "safe securities" and sold them off to pension and life insurance plans. They bankrupted their competitors and moved the legacy debt (and responsibility) onto taxpayers like you and me.
Wall Street firms operate with tons of "other people's money" ("OPM," or oh-pum, as they call it)... And they use it to make tons more money by creating bubbles and then getting out.
They collect billions of dollars in fees and commissions as the bubble expands. But it's the clients who are left holding the worthless "investments" when the whole thing blows up.
Never forget, Wall Street doesn't care about you or helping you enjoy a healthy retirement.
But the question is: If it's easy to pinpoint when events like the tech bubble and the mortgage crisis were reaching their breaking points, why were so many people blind to them at the time?
The answer is human nature...
The most critical component is the foible of behavior called self-serving bias.
Most people and investors only see what serves their best interest. They only look at facts in the context that fits their portfolio or their beliefs. It's like when athletes credit themselves and their preparation when they win... but blame referees, weather, or some other external factors when they lose.
It happens in bull markets, too... when everybody and his neighbor claims it's their stock-picking skills that make them so much money.
This bias preserves egos and makes many people feel better about the good news and less bad about the bad news.
But this self-serving bias while investing is dangerous... It helps you get caught up in bubbles and makes you think you're smarter than you really are. It will leave you holding the bag – and major losses – when the Wall Street crowd bails out ahead of you.
Longtime readers know that I spent a decade as an elite Wall Street trader... including as a Goldman Sachs vice president. But these days, I dedicate my time to helping regular folks beat the pros.
And I'm not the only former Wall Streeter doing this... My friend and colleague Marc Chaikin also left Wall Street to help everyday investors.
Right now, Marc is sounding an urgent warning as we head into 2026. He's pointing to a rare market signal he calls the "January Trigger."
This signal has preceded periods of serious market weakness every single time it has appeared since 1950. This isn't an unimaginable "black swan." But Marc believes it could once again spell trouble for unprepared investors...
Yesterday, he went live to share the one straightforward money move to make in the coming days as this urgent situation plays out. He also shared one stock to buy and another to avoid or sell immediately.
If you missed it, don't worry – you can catch up on all the details here.
Now, let's get to this week's Q&A... And as always, keep sending your comments, questions, and topic suggestions to feedback@healthandwealthbulletin.com. My team and I read every e-mail.
A New Definition of Obesity
Q: I just saw on the news that most people are "obese" now according to a new definition. Thoughts from you, Doc? – P.J.
A: For decades, the body mass index ("BMI") has been the standard to determine if someone is obese. Your BMI calculation comes from dividing your weight (in kilograms) by your height (in meters squared).
But in October, researchers at Mass General Brigham and Harvard Medical conducted a study with more than 300,000 adults to create a new definition of obesity.
Instead of just using BMI, researchers also looked at a person's anthropometric measurements: their waist circumference, waist-to-hip ratio, and waist-to-height ratio. To be classified as obese, a person needed to have:
(1) elevated BMI plus at least 1 elevated anthropometric measure or BMI greater than 40; (2) at least 2 elevated anthropometric measures, irrespective of BMI; or (3) excess body fat.
What they found with this new definition is that nearly 70% of American adults are likely obese, compared with previous estimates of about 40%.
Regular Health & Wealth Bulletin readers have heard for years that using your BMI as a primary indicator of your health is critically flawed... As I explained in Tuesday's issue, my own favorite indicator is waist circumference. It's the most likely to highlight our bodies' dangerous visceral fat.
The new metric you cited, P.J., is a big improvement over BMI. If you are obese based on either this approach or your waist size, it's time to take action. Increase your physical activity and consider the Mediterranean diet.
Numbers like these are only one of many factors that make up your overall health picture. But if they're giving you a warning, don't ignore it.
What We're Reading...
- Did you miss it? What to expect for stocks in 2026.
- Something different: Humans made poisoned arrowheads thousands of years earlier than previously thought.
Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
January 9, 2026