The One Mistake That Turns a Bad Year Into a Permanent Loss

What You Will Learn From This Article

• Why Munger and Buffett both singled out leverage as uniquely dangerous, compared to ordinary investment risk
• The specific mechanism by which borrowed money turns a temporary decline into a permanent loss
• Where this shows up beyond obvious margin trading
• How to tell whether you’re carrying investment leverage without necessarily thinking of it that way

Almost every investment carries some risk of loss. Very few things can turn a strategy that would otherwise have worked out fine into total ruin. Munger and Buffett, independently and repeatedly across decades of interviews and shareholder letters, named the same one: borrowed money.

Why Leverage Is a Different Category of Risk

Ordinary investment risk means a position might decline in value. If you own the asset outright, a decline is a paper loss, uncomfortable, but survivable, provided you can afford to wait for a recovery and the underlying case for owning it hasn’t actually changed. Time is on your side, because nobody can force you to sell at the bottom.

Leverage removes that option. When a position is bought with borrowed money, a decline of a certain size can trigger a margin call, a demand from the lender for more collateral or immediate repayment, regardless of whether you believe the position will eventually recover. This forces a sale at exactly the worst possible moment, converting a temporary decline into a permanent, realised loss, often at the precise point of maximum pessimism, right before a recovery that the leveraged investor never gets to participate in.

This is the specific mechanism both men have pointed to. Buffett has noted that with enough leverage and enough time, it’s possible to turn a strategy with a very high probability of long-term success into one with a real chance of ruin, simply because leverage removes your ability to survive being right eventually if you can’t first survive being wrong temporarily.

Where Leverage Shows Up, Beyond the Obvious

Margin trading, deliberately borrowing against a brokerage account to buy more securities than your own capital would allow, is the most direct and obvious form. But leverage shows up in less obvious ways too, and it’s worth recognising all of them:

• Borrowing against a home to invest in the market, which means a downturn now threatens your housing situation alongside your investment portfolio
• Using a bridging loan or short-term credit to hold an investment position you couldn’t otherwise afford to hold through a downturn
• Investing money you’ll genuinely need within a fixed, short timeframe, which functions similarly to leverage even without a literal loan, since it removes your ability to simply wait out a decline
• Concentrated positions funded partly by debt in a single business, property, or asset, rather than a diversified portfolio

The common thread across all of these is the same: something external to your own investment judgement, a lender, a bank, or a hard deadline for needing the cash, can force a decision at a time you don’t choose.

The Real Cost, in Plain Terms

The cost of unleveraged risk, taken sensibly, is volatility you can ride out. The cost of leveraged risk, when it goes wrong, is capital that doesn’t come back, because you were forced to sell before the recovery that might otherwise have arrived. Many investors who were fundamentally right about a long-term trend have still gone broke, purely because they couldn’t survive the short-term decline that came before being proven right.

Checking Your Own Exposure

• Could a market decline of 30% or 40% force you to sell any part of your portfolio, due to a loan, margin requirement, or a genuine need for that specific cash within the next few years?
• If the answer is yes, that position is functioning as leveraged risk, whether or not you think of it that way
• Before taking on any form of borrowing to invest, ask specifically what would happen to your position in a downturn severe enough to trigger a margin call or forced sale, not just what you expect to happen if things go well
• Keep enough unencumbered capital or cash reserve that a market decline never forces a decision on your timeline rather than your own

Key Takeaways

• Munger and Buffett both identified leverage, more than almost any other single factor, as capable of turning a sound long-term strategy into permanent ruin
• The mechanism is specific: leverage can force a sale during a temporary decline, converting a survivable paper loss into an unrecoverable, realised one
• Leverage isn’t limited to formal margin trading, borrowing against a home, bridging finance, or investing money you’ll need on a fixed near-term deadline all function similarly
• The practical defence is ensuring no external party or deadline can force a sale during a downturn, so that time remains on your side

Frequently Asked Questions

Does this mean all borrowing to invest is a mistake?

Not automatically, but it changes the risk profile fundamentally, since it introduces a party or a deadline that can force a decision regardless of your own judgement. Anyone considering it should specifically model what happens to their position in a severe, prolonged downturn, not just the expected favourable case.

How is investing money I’ll need soon similar to leverage, if there’s no actual loan involved?

Both situations remove your ability to simply wait out a temporary decline. With leverage, a lender can force the sale. With a near-term cash need, your own circumstances force it. The forcing mechanism differs, but the practical effect, being unable to wait for a recovery, is the same.

Is a home loan used to buy an investment property the same kind of leverage risk?

It carries a related risk, since a severe downturn combined with an inability to service the loan could force a sale at a bad time. The specific risk depends heavily on the loan terms, your income stability, and how much of a buffer you hold, so it’s worth modelling explicitly rather than assuming it’s automatically safe because property is involved.

Can a cash reserve fully protect against leverage risk?

A sufficient cash reserve significantly reduces the risk of a forced sale by covering margin calls or near-term needs without touching the invested position, but it doesn’t eliminate risk from borrowing itself, since a large enough decline can still exceed what any reserve was sized for.

Why do intelligent, experienced investors still get caught by leverage?

Often because the leverage was taken on during a period when markets were calm and rising, when a severe downturn felt unlikely enough to model seriously. Munger and Buffett’s repeated warnings on this specific point exist precisely because experience and intelligence don’t automatically protect against it.

This article was researched and drafted with the assistance of AI tools and reviewed for accuracy. It is general information, not personalised financial advice. Historical and biographical details were verified against publicly available sources at the time of writing, but please confirm any date or fact that matters to you independently before relying on it.