How often should you check your investment portfolio?
- Robin Powell
- May 22
- 8 min read
Updated: May 26
Some retail investors check their portfolios several times a week, for no good reason and to no useful end. The behavioural literature has settled on a clear answer to how often they should — almost never.
It's early evening on a weekday. You're not doing anything in particular. The phone is on the arm of the sofa. You pick it up, open your platform, and look at the number. The market closed an hour ago. Nothing you see can change anything you'll do. You look anyway.
How often to check your investment portfolio is one of the more consequential decisions a long-term investor makes, and the evidence on the question is now substantial enough to answer it directly. The entry point for what follows is Risk & Reward, a new book by Ben Carlson, published by Harriman House.
The story Carlson keeps telling
Carlson is Director of Institutional Asset Management at Ritholtz Wealth Management and the author of the A Wealth of Common Sense blog. The story he keeps returning to is about a man called Bob.
Bob started saving in 1970, aged 22. He put aside $2,000 a year initially, raising the figure by $2,000 each decade. Over more than 40 years he saved $184,000. He was also, by his own admission in Carlson's hands, the worst market timer who ever lived. The $6,000 he invested at the start of the 1973–74 bear market lost half its value. So did the $46,000 he put in just before Black Monday in October 1987. He bought $68,000 of equities at the dot-com peak in 2000. He bought another $64,000 just before the 2007 crash. By the time he retired at 65, his portfolio was worth $1.1 million.
Carlson's framing is Churchillian. 'Many forms of investing have been tried and will be tried,' he writes in the introduction. 'Long-term investing is not perfect or all-wise. Buy and hold is the worst form of investing, except for all those other investment strategies that have been tried from time to time.'
The conventional reading of Bob is that patience was his superpower. The closer reading is that his patience was never tested in the form the modern investor's is. Bob had no app. He had no notifications. He had no daily price tracker and no refresh-and-see-the-number reflex. The thing that made Bob's portfolio recoverable was the thing today's reader has lost.
The cost of looking
The smartphone has done to investing what the slot machine did to gambling — taken a long-horizon activity and given it a short-horizon interface, complete with red and green colour coding, percentage badges and live price feeds. The behaviour is universal. The diagnosis isn't the investor; it's the room they are standing in.
Daniel Kahneman's central insight, returned to throughout Risk and Reward, is that losses sting roughly twice as much as equivalent gains feel good. Richard Thaler extended the point to the question of how investors monitor their holdings. Because losses are more frequent at short horizons than long ones, the more often you look the more often you experience the sting. He called it myopic loss aversion.
Tennis player Andre Agassi, of all people, put it more cleanly than any academic. In his memoir Open, quoted by Carlson, he writes: 'A win doesn't feel as good as a loss feels bad, and the good feeling doesn't last as long as the bad. Not even close.' He was talking about tennis. The mechanism is the same.
Carlson's own data make the case structurally. His Chapter 6 reproduces a table of S&P 500 loss rates by holding period from 1950 to 2024, drawn from YCharts. Over a single trading day, 44 per cent of observations are negative. Over a month, 36 per cent. Stretch the horizon to a year and the figure falls to 19 per cent. Five years cuts it to 5 per cent. Over 10 and 20 years, on this sample, the loss rate is zero.
The implication is unambiguous. Check daily, and the arithmetic guarantees a bad feeling roughly four days in every nine. Check yearly, and the bad feeling arrives, on average, about once every five years. The portfolio is the same. The investor's experience of it is not.
Carlson quotes Kahneman on this point directly, from his Nobel acceptance lecture in Stockholm on 8 December 2002: 'the long term is not where life is lived.'
The field-experiment evidence makes the same case in cleaner form. Francis Larson, John List and Robert Metcalfe, in NBER Working Paper 22605, ran a natural field experiment with professional traders at a London firm. The traders given infrequent price updates invested 33 per cent more in risky assets than those updated frequently, and earned 53 per cent higher profits. These were experienced market professionals, not retail investors. Looking less worked.
The case gets harder when you leave the US
Carlson concedes the awkward part of the argument himself. The 'now show Japan' challenge — the thought experiment in which an American investor's faith in equity returns is tested against the data from a developed market that did not behave like the US — sits in his own framing. The piece that follows is building on his concession.
The structural fact behind the challenge: the US share of global equity market capitalisation rose from around 15 per cent in 1900 to roughly 60 per cent in 2023. Winners write the data.
A paper by Aizhan Anarkulova, Scott Cederburg and Michael O'Doherty, published in the Journal of Financial Economics in 2022, set out to address the bias. The authors built a bootstrap simulation of long-horizon equity outcomes across 39 developed countries from 1841 to 2019. The methodology was designed to treat losing markets as data, not as gaps in the record.
The finding sits well outside the US-only frame Carlson works within. The authors estimate a 12 per cent probability that a diversified equity investor with a 30-year horizon loses money in real terms. The same simulation applied to the US-only sample gives a 1.2 per cent probability. Ten times higher. At the bottom of the distribution, in the 1st percentile of 30-year outcomes, the real value of $1 invested falls to 14 cents.
These figures are stress tests, not forecasts. The next 30 years may resemble the global past, the US past, or neither. No serious analyst pretends otherwise. The figures are useful as a calibration of how rough the long-horizon path can be, not as a prediction of where it will run.
The implication brings the question back to its spine. If the path to a long-horizon equity outcome is rougher than US data alone suggests, the behavioural cost of frequent checking is higher, not lower. A path with deeper drawdowns is a path that tests the watcher more often. Every check during a deeper drawdown is another act of loss-aversion arithmetic, another opportunity for the investor to act on the worst possible information. The case for not looking is sharpened by the global evidence, not softened.
What Japan made people do
The Anarkulova distribution becomes concrete in Japan. The TOPIX and Nikkei 225 peaked in December 1989 and fell roughly 69 per cent peak-to-trough by 2003. The Nikkei 225 did not close above its 1989 high until February 2024 — about 34 years after the peak.
A Japanese investor who reinvested dividends through the lost decades fared better than the headline price index suggests. Cumulative total return in yen since the end of 1987, on MSCI data, was roughly 1,400 per cent for global stocks against roughly 49 per cent for Japanese equities. The diversified investor did far better than either headline figure implies for a single-country bet. The investor whose attention was glued to the home index did far worse. Both could see the same screen.
The point is not that Japan tells the world what to fear about the next 30 years. The point is what happened to the people who watched. In a market that goes down for three decades the patient cohort thins. Households with every cultural, demographic and institutional reason to hold equities sold and stayed out through what was, eventually, a recovery. The investors who fared worst in Japan were not those who held. They were those who watched.
A concession the case survives: Japan may have been sui generis. Reasonable readers read the episode differently. But the lesson does not depend on Japan as a generalised forecast. It depends only on Japan being a real market in which the path tested the watcher more than it tested the holder. On that, the record is clear.
Change the room, not the resident
The honest answer to how often you should check your investment portfolio is: almost never. The discipline this requires, though, is not what readers expect. It is not willpower. Willpower is unreliable, finite and unrelated to long-term investment outcomes. The discipline is structural. Change the environment around the decision and the decision mostly takes care of itself.
Four moves, in order of leverage.
The first is to set a cadence and write it down. Quarterly is plenty. Annual is better for most investors still in the accumulation phase. The act of pre-committing to a schedule is the architecture move; the schedule itself is secondary. A diary entry that reads 'review portfolio: 1 December' is doing work no resolution to check less often will do.
The second is to delete the app. Not 'turn off notifications', not 'move it to the second screen' — delete it. If you need to check, do it deliberately, from a desktop browser, having made a small effort. Friction is the entire point. In a world built to reduce the effort of looking, the investor's job is to put the effort back in.
The third is to change the question you ask when you do check. 'How is my portfolio doing?' has a daily answer, and the daily answer is mostly noise. 'Am I still on track to meet my goal?' has an annual answer, and the annual answer is signal. The same investor with the same portfolio can be calm one moment and panicked the next, depending on which question is in their head.
The fourth, and most underrated, is to watch your savings rate rather than your returns. Carlson makes the point in his conclusion. Bob's $1.1 million was driven primarily by what he saved, not by what the market did. The savings rate is something the investor controls. The returns are not.
Carlson's closing line in Risk and Reward earns its place because the case it summarises has been made: 'You don't need to outsmart the market. You just need to outlast it.'
The architecture is how you outlast it. Change the room, not the resident.
Bob did not have more patience than the reader of this piece. He had a worse phone.
Resources
Anarkulova, A., Cederburg, S., & O'Doherty, M. S. (2022). Stocks for the long run? Evidence from a broad sample of developed markets. Journal of Financial Economics, 143(1), 409–433.
Carlson, B. (2026). Risk and reward: How to handle market volatility and build long-term wealth. Harriman House.
Kahneman, D. (2002). Maps of bounded rationality: A perspective on intuitive judgment and choice. Nobel Prize lecture, 8 December 2002, Stockholm.
Larson, F., List, J. A., & Metcalfe, R. D. (2016). Can myopic loss aversion explain the equity premium puzzle? Evidence from a natural field experiment with professional traders (NBER Working Paper No. 22605). National Bureau of Economic Research.
Thaler, R. H., Tversky, A., Kahneman, D., & Schwartz, A. (1997). The effect of myopia and loss aversion on risk taking: An experimental test. Quarterly Journal of Economics, 112(2), 647–661.
Where to go from here
The question this piece sets out to answer is the kind of practical, behavioural question that How to Fund the Life You Want by TEBI editor Robin Powell and Jonathan Hollow exists to address. The newly-published second edition is written for UK readers thinking about how to set up an investing life that does not depend on willpower to keep working. You can buy it on Amazon.
For readers who would prefer a professional in the conversation, TEBI's Find an Adviser directory lists advisers who have publicly committed to evidence-based investing.
If you'd rather work with someone who already thinks this way, our Find an adviser directory lists firms that have publicly committed to low-cost, globally diversified, evidence-based investing.