In tennis, golf, and other individual sports, the most successful players are typically those who commit the fewest unforced errors. The same is true for investing. Successful investors have learned to keep mistakes to a minimum.
In his new book, How Not to Invest, money manager Barry Ritholtz chronicles many of the most common mistakes investors make. In the following excerpt, he highlights errors to avoid — and explains what to do instead.
This book is designed to reduce mistakes — your mistakes — with money. Tiny errors, epic fails, and everything in between. If only you could learn how to avoid the avoidable errors investors make all the time, your life would be so much richer and less stressful!
That is my charge: To share what I have learned so you can skip the most common mistakes people make with their capital. Avoid these unforced errors and your financial well-being will eclipse 90% of your peers.
Most finance authors don’t take this approach. The typical investing book goes the “How-To” route. They want to teach you — in a dozen chapters or so — everything you need to learn to become financially successful. Execute these 100 strategies, and start adding up the dollars!
That approach fails in the real world. Even if you do all the right things, it only takes a few mistakes to undo all your prior efforts.
This truth is counterintuitive: Avoiding errors is more important than scoring wins. This wonderful insight came from investment consultant Charley Ellis in a 1975 Financial Analysts Journal paper titled “The Loser’s Game.” Investing, Ellis observed, is similar to tennis, in that most people lose by making unforced errors. The way to win the “loser’s game” is simply to lose less: Make fewer errors, and let the other guy beat themselves. A decade later, Ellis expanded this thesis into his classic book Winning the Loser’s Game.
How Not To Invest will do that too: In the modern context of social media, reddit memes, and 24/7 news, I am going to teach you to avoid the many mistakes that undo most investors. More simply stated: Make fewer errors, make more money.
Berkshire Hathaway’s inimitable Charlie Munger phrased it this way: “It’s remarkable how much long-term advantage people like us have gotten by trying to be consistently not stupid, instead of trying to be very intelligent.”
I am going to review the most common errors investors make; I will show you the myths that so many firmly believe to their detriment. I’ll include some favorite mistakes, including a few of my own, as well as lessons from the wealthiest and most error-prone investors.
All humans are fallible. That is the very nature of what it means to be human; we have a limited ability to see the future or even understand the past and present. We all make mistakes. This book will help you make fewer of them; those you do make will be less expensive.
The goal is the same as Munger’s: “Consistently less stupid.”
Outcomes versus process
Sports fans and investors tend to make similar errors. Perhaps the biggest is focusing on outcomes rather than process. Sports fanatics are all Monday morning quarterbacks; they can read you chapter and verse — after the fact — what should have been done late in the game on 4th-and-goal from the two-yard line.
It’s called “hindsight bias,” and it afflicts investors, too. They can tell you what asset classes you should have owned last year, which hedge fund manager you should have invested with 20 years ago, and why you should have bought Netflix, Tesla, and Apple about 5,000% ago. Thanks for nothing!
So, what is process, and how does it differ from outcome? Process is the methodology used to accomplish an undertaking. It could be a simple checklist or a complex systematic approach. Process focuses on the specific actions that must be taken, regardless of the results.
Outcome is the result; it could be due to skill, luck, and intelligence, plus numerous other random factors. At the end of the day, outcome is who won or lost the game, how many planes landed safely, what stocks went up or down, and what surgical patients lived or died.
In sports terms, think of process as your playbook and outcome as the final score. In investing, process is your approach, investment style, discipline, and consistency, while outcome is your return or performance.
Imagine you are watching two people in a coin-flipping contest. One of them flips 10 heads in a row; the other’s flips are more random— heads, tails, tails, heads, tails, etc. Are you willing to bet a substantial sum that the first flipper’s next toss will be heads? If you said yes, you are outcome-focused.
We all tend to be outcome-focused, often to the detriment of choosing a good process.
Perhaps an example from outside of the world of finance might be helpful. Imagine you have a medical condition that requires surgery. It’s a bit tricky, but the procedure has a good chance of success. You interview a few doctors, looking at their academic history, published papers, experience, and reputations. You narrow the list to two surgeons and get access to their surgical records, including patient survival rates.
Both surgeons have very good reputations; one works primarily for private patients covered by insurance, the other is at a top medical school.
The private doctor runs a success/survival rate of 86%, while the medical school doc runs at 61%.
Which doctor do you choose?
If you immediately said the 86% doctor, you are outcome-focused. You saw the better results and that was all you needed to know. World Series of Poker Tournament Champion Annie Duke, in her 2018 book Thinking in Bets, calls this “resulting.” This is the cognitive error of evaluating decisions based solely on their outcomes, rather than on the quality of the decision-making process behind them.
Instead of “resulting,” you might have wondered why a cutter with a great reputation at a top-ranked medical school had a much worse survival ratio. You do a little more research into her process. You find that she invented this procedure 30 years ago.
She did all of the early experimental surgeries, including lots of clinical failures (meaning bad surgical outcomes and low survival rates). But over time, she refined the surgery, where through trial and error she developed what is now a life-saving technique. Indeed, her methodology has become the standard, thanks to her research. Every doctor and patient who followed afterward benefited from her groundbreaking clinical work.
Because of her background in this area, this doc gets all of the “impossible” surgical cases. When other surgeons don’t think they can do the operation — or don’t want to negatively impact their batting average — they refer it to her medical school. Hopeless and complicated surgeries make up a big part of her practice. People travel from around the world just to have this surgeon do this procedure on them. She has seen every variation of patient, and because of this, she has done more of these operations than anyone in the world.
Based on this new information, which surgeon would you choose? The first doctor was pretty good, but the second doctor is outstanding! If you suddenly are thinking about the medical school doctor with the lower success rate, well, congratulations — you have just become process-focused.
The key to focusing more on process is to understand that good outcomes follow good processes. Without understanding the underlying process, good outcomes could just as likely be due to dumb luck as to skill.
You should be reminded of this every time you read the disclaimer “past performance is no guarantee of future results.” What you are actually seeing is an admission of random outcomes. When past performance is the result of luck, then it provides zero insight into what future results might look like.
We rarely know precisely what the sources of good outcomes are; however, we have a high degree of confidence what the probabilities are for a good process. A strong process is a guarantee not of outcome or results, but of a higher probability of obtaining your desired results.
That’s why process is so important to investors.
Risk is unavoidable. Panic is optional.
The easiest button to press is the one marked “Sell.” It’s a salve for your emotional distress, especially when facing volatile, disruptive stock markets. Panic selling might ease your upset stomach or help you sleep better, but it wreaks havoc on your portfolio.
The single biggest challenge of panic selling equities: How do you get back in? When? What determines your repurchase decision? What metrics do you base this Buy upon?
My experience with panic selling was deeply influenced by the investor behavior I observed during the 2000 dotcom implosion, 2008-09 financial crisis, and the 2020 pandemic sell-off. (Other asset managers have had similar experiences.)
It’s more than mere anecdotal — we have hard evidence to back up what makes panic selling so bad. A very interesting study examined what happened when freaked-out investors panic-sold. The study was based on “the financial activity of 653,455 anonymous accounts corresponding to 298,556 households from one of the largest brokerage firms in the United States.”
An amusing finding: “Investors who are male, or above the age of 45, or married, or have more dependents, or who self-identify as having excellent investment experience or knowledge tend to freak out with greater frequency.”
But that buries the lead. The more important issue is what those investors who panic-dumped their equity portfolios did subsequently. The most important takeaway trom this research: “We find that 30.9% of the investors who panic sell never return to reinvest in risky assets.”
That is an astonishing data point: Nearly a third of investors who panic sell never buy equities again — ever! The rest of the panic-sellers repurchase equities at higher — often MUCH higher — prices than they sold for. These buys tend to be later in the recovery once the news flow improves — markets bottom when the headlines are horrific, leading to this emotional capitulation.
[SMI note: It was our observation of investor panic selling during the 2000 and 2008 bear markets that led to the development of SMI's bear-market selling disciplines. The key distinction is that these disciplines are predetermined, rules-based processes, not emotional panic selling. Knowing these rules-based processes exist helps SMI members not panic sell.]
Panic-selling is easy, getting back in at the lows is hard, not ever getting back in is ruinous.
In markets, panic does not make anything better and often makes things worse — and occasionally much worse.
Do’s and don’ts of market crashes
Every few quarters, we find ourselves running through the same muster drill. Something happens somewhere in the world, and the markets go a little wild. They sell off a dozen percent or so. The usual suspects panic. Eventually, things stabilize, and everyone wonders what just happened. Post-mortem explanations come along that seem reasonable (after the fact, of course, never before).
Lather, rinse, repeat.
The phones ring with reporters wanting a comment on the volatility. “What’s going on in the markets?” they say. My response is always the same: “You won’t like my answer: This is what markets do — they go up and down, sometimes violently.” “Thank you,” they say as they hurriedly hang up.
I can do the drill in my sleep. End of 2015? China down 15%, Europe off the same. Fourth quarter of 2018? S&P 500 off ~20%. Q1 2020? S&P 500 down 34%. 2022, stock markets off 20%, Nasdaq down over 30%, and the bond market off 15%! Summer 2024, Japan falls 9% in two days!
Any given week can have a surprise in store, which then cascades around the world. It’s almost as if this is a pattern, a normal part of markets!
My colleague Callie Cox has run the numbers. On a typical day, the market swings ~0.5%. In fact, Callie observes, “the S&P 500 has gained or lost less than 0.5% on 53% of trading days.” Plus or minus 1% days occur about 20% of the time. That averages out to once a week, but “it isn’t a predictable, once-every-five-days type deal.”
Drawdowns of 5-10% happen more than you might realize — there have been 57 sell-offs of that size since 1950 (that’s two out of every three years). There have been 23 sell-offs of more than 10% and less than 20% over that time (once every three years). And over the past 75 years, there have been 11 drops in the S&P 500 of 20% or more.
When the usual occurs, my advice is always the same: Turn off the TV, follow your plan, and start flipping over couch cushions to find spare cash, because a wonderful buying opportunity is coming your way.
Let’s get more specific as to the “Do’s and Don’ts” of market crashes:
Do notice how cyclical markets are.
Markets rise and fall with shocking regularity. They may not stick to schedules as tightly as the solar system does — think seasons, sunrise and sunsets, moon phases, even the appearance of comets — but they do move in semi-regular cycles. As do market corrections and crashes.Between 1950 and 2014, half of all annual periods saw a correction of 10% or more. Bull and bear markets come along on their own timelines, stay for as long as they like, then move on. There is not a whole lot you can do about it, except recognize that it happens.
Don’t react emotionally.
Do not give in to your gut, which might cause a momentary lapse in reason. That knot in your stomach, sweaty palms, accelerated breathing, and increased heart rate are signs of stress. The discomfort is a feature, not a bug. This agitation is supposed to crank up your body and make it ready to react to danger...but it works against you in the capital markets. Adrenaline, it turns out, is not the basis of sound judgment or portfolio management.Do notice your own state of mind.
Notice the subtle difference between reacting emotionally to external stimuli and that nagging feeling that you forgot something important. At times, your body may be telling you something. Is your portfolio in sync with your own risk tolerance? Are you carrying more exposure to high-risk assets than you are comfortable with? Have your circumstances changed, but your portfolio has not? Try to be perceptive when your subconscious is trying to get you to notice something. It could be important.Do stick with your plan.
You made a long-term plan in the first place for money you do not need access to in the next year (or for years after), but rather, decades from now. In 2050, you will not care what the market did in April 2025. The short term always seems to get in the way of the long term. I’ve heard countless stories from investors who panicked out of the market at the March 2009 lows and never found their way back in. They missed out on a huge climb in value. That’s not sticking to a plan, and it’s not what good financial planning looks like.Don’t rely on gurus, shamans, or talking heads.
They haven’t the slightest idea about your financial needs, your risk tolerances, your tax bracket, or anything else about you. I have been doing financial TV and radio for more than 20 years and have met many of these people. Very few have the slightest idea what they are talking about, and their general advice is for entertainment purposes only. Their forecasts are nothing more than marketing. Treat them that way.Don’t take action while in a state of discomfort.
Decisions made to stop the pain are the ones you will regret. The time for action is when you are in a calm state of mind. Any significant financial decision you make should be circumspect, carefully considered, and according to plan. If you are merely reacting to the latest market moves, breaking news, or headlines, then what you have is not a plan — you have an instinctual, fear-driven reaction, and that’s the makings of a disaster.Do take notice of the panic around you.
Watch the reactions — and overreactions — of the guests on financial television. How emotional and strident are they? Are their voices up an octave? Can you see them sweating? There is a feedback loop from markets to TV anchors and back — see if you can spot it. Just don’t let yourself become affected by it.Don’t try to time the markets.
You lack the skill, the discipline, and the ability. Even if you get lucky, it’s just that — dumb luck — and that serendipity is likely to encourage you to engage in even more reckless and foolish behavior in the future. The odds of you jumping out on time and getting back in at or near the lows are stacked against you. Add in taxes and other costs, and it becomes a fool’s errand.Don’t confuse the short term for the long term.
The day-to-day action is noise unless you are an active trader doing this for a living. You will lose money treating investments like trades and vice versa.
Have a plan. Stick to it.
Here is the drill: The debacle du jour occurs; Klaxon horns sound, lights flash, and suddenly, everyone is urging you to take action — do something! Anything! — about these important breaking news items. Pandemic! War! Crash! No matter what occurs, someone is urging you to update your portfolio.
My best advice: Always ignore them.
Maybe it was the Flash Crash, the US fiscal cliff, Brexit (Grexit, too), a 20% drawdown in Q4 2018, a continuing resolution funding bill, the 34% pandemic crash, the Russian invasion of Ukraine, or the Israeli/Hamas/ Hezbollah (and Iran?) war. Maybe it was the 18% S&P 500 slide with a 33% crash in the Nasdaq 100 in 2022.
Regardless of the event, you are told to rouse yourself from your slumber and get busy getting busy.
My charge is constantly reminding people that the best time to read the safety card on the seatback in front of them is before their jet takes off. At 30,000 feet, with one engine out and the other on fire, you probably missed the best opportunity to think calmly and clearly about your options.
Planning ahead allows you to make decisions rationally and free from emotional distress. Waiting until trouble hits to decide what to do means you are likely deferring to your limbic system, which is the path to panicky decision-making.
It’s the same every time: Something bad happens somewhere, and markets become unhinged. A substantial sell-off ensues, and the usual suspects panic.
The noise subsides, markets settle down, and everyone returns to their originally scheduled programming.
One thing the perma-bears never inform you in their never-ending parade of Armageddon forecasts is that there is always a reason to sell stocks. The problem with those reasons is they rarely turn out to be smart, or work in the investor’s favor.
We discussed earlier that markets move less than half a percent on 53% of the trading days; really big moves of 5% to 10% occur in two out of every three years; and sell-offs between 10% and 20% happen once every three years. This is what normal looks like.
What should investors think about as these events happen? Here is my shortlist:
Markets surge and sell-off. This is the ordinary course of events.
Emotional reactions are bad for your portfolios.
The world is filled with random outcomes. Even more so when humans are involved.
Gurus and talking heads will fail you. Their forecasts were wrong. Most didn’t see THIS coming, whatever THIS is.
What sounds sexy and looks good in a brochure or website is not what usually makes you money over the long run.
You need a plan and the discipline to stick with it.
“Nobody knows anything” is a truism about the future. It also applies to nearly everything in life. Internalize it.
Your brain is designed to keep you alive in changing conditions, not to make capital risk/reward decisions.
Bull and bear markets have their own timelines. They do not care about your retirement, savings for your kid’s college, or the new house you want to buy.
“Uncertainty” is a misnomer. When you hear people using the word “uncertainty,” it is because they are scared enough to briefly acknowledge their own ignorance.
Neither adrenaline nor dopamine is the basis of sound decision-making.
All predictions are marketing (not advice).
The future is inherently unknown and unknowable. Those who claim otherwise are selling something.
Investing is hard.
If you learn nothing else, at least learn this: Never confuse day-to-day noise with an actual reason to make a change in your portfolio. If you are merely reacting to the latest market action, then what you have is not a plan — you have instinctual, fear-driven behavior, and it’s the makings of a disaster.
Or, as Blaise Pascal, the French mathematician and philosopher, once observed, “All of humanity’s problems stem from man’s inability to sit quietly in a room alone.”