Across nearly three decades of monthly investing (1997–2025), Mobius’s data shows that longer periods dramatically improve the odds of positive returns.

Summary

Longer investment periods sharply improve the odds of success. The returns from short investment windows swing wildly—from deep losses to dazzling gains—but as you extend to 3, 5, and 10 years, volatility compresses and positive results dominate. Over our full history (October 1997 to December 2025), the one‑year return ranged from about −48% to +64%, while 10‑year returns were consistently positive. The lesson is clear: outcomes depend less on picking the right moment, and more on staying invested through cycles and letting time do the compounding.

Mobius’s success ratios underline this point. Across all possible permutations of 1‑, 3‑, 5‑, and 10‑year periods, the probability of a positive return was 69%, 81%, 92%, and 100% respectively. For example, every one of the 219 ten‑year periods delivered a positive return, while 256 of 279 five‑year periods (92%) were positive. In other words, if you invested in any month of the first 18 years of Mobius for a period of 10 years, you would have made money.

Timing the Market

 “Timing the market” describes the challenge investors face when deciding whether to exit or re‑enter during global turmoil. It is not about a single portfolio or sector, but about broad macro swings. The difficulty lies in judging both the exit and the re‑entry. Many investors claim to have sold at the right time, but often reinvested too late. When prices are low, bad news dominates, so investors wait for stability—by which time markets have already risen. Historical data consistently shows the benefits of staying invested rather than attempting to time the market.

Studies on the FTSE All‑Share confirm this: the longer the timeframe, the greater the chance of success. Hargreaves Lansdown, for example, reviewed 1‑, 3‑, 5‑, and 10‑year horizons over 30 years and found that longer horizons overwhelmingly produced positive returns.

Current Investment Climate

The Mobius club’s lifetime (1997–2025) has spanned crises that shook markets: the 2000 dot‑com bubble, the 2008 global financial crisis, the 2016 Brexit vote, the 2019 Covid pandemic, the 2022 Ukraine crisis and the recent wave of US-China trade frictions & worldwide tariff escalations. Each triggered sharp drops, yet each was followed by recovery. The NASDAQ fell 77% between 2000 and 2002, the Dow dropped 54% from 2007 to 2009, and Covid erased a third of the Dow’s value in March 2020 before new highs later that year. Brexit and Ukraine caused steep one‑day falls in the FTSE 100, but both stabilised quickly. These episodes highlight how crises can cause violent short‑term losses, yet long‑term investors who stay invested typically see recovery.

Method Used

We tested the familiar claim: “time in the market matters more than timing the market". Using Mobius’s monthly unit values, we calculated rolling annualised returns (AER) over 1‑, 3‑, 5‑, and 10‑year timespans from October 1997 through December 2025. This captures what investors actually experience when committing capital monthly and holding for different periods. The experiment uses a “multi‑period, all‑permutations test". For each duration, we examined every possible rolling period.

For example, in a three‑year span from September 2017 to August 2020, there are 25 possible one‑year periods: The 25 combinations of 1-year (on a rolling one-month basis) are: Starting from Sept-17 to Aug-18, Oct-17-Sept18, Nov17-Oct18, all the way to Aug19-Jul20 and finally Sept-19-Aug20. We counted how many 1-year periods had a positive AER, then divided by the number of 1-year periods to define the success ratio. 

Mobius Club Results

The results are striking. Of 327 one‑year periods, 226 (69%) were positive. For three years, 246 of 303 periods (81%) were positive. For five years, 256 of 279 (92%) were positive. And for ten years, all 219 periods (100%) were positive.  

It is easy to see why five years is often cited as a minimum timeframe—beyond this, the probability of loss is greatly reduced. The investment profile assumes regular monthly contributions, reflecting the common pattern for UK investment clubs such as Mobius.

Drilling Further

Looking deeper, the range of returns narrows with time. For one‑year period, the lowest return was −48% (June 2001) and the highest +64% (May 2021). For ten‑year periods, the range was +1.3% to +20.3%. Average returns rise slightly with horizon, while standard deviation falls. This strengthens the case for longer timeframes: volatility compresses, and outcomes become more predictable.

The distribution curves below show an overlay of AERs spread over all four periods, showing how volatility narrows with time. 

The Tipping Point: Minimum Period for Certainty

We also wanted to find out the shortest investment horizon that always gave a positive return. For the Mobius dataset, the tipping point is 86 months (7 years and 2 months). Any monthly investment held for at least this period delivered a positive AER. Beyond this horizon, time fully neutralises shocks—patience, not timing, guarantees success. This number is probably a mathematical curiosity, but it underlines  the power of compounding over time.

 Five More Years of Perspective

When we last published in early 2021, our dataset ran through August 2020. At that point, the Covid crash had only just unfolded, and many of the rolling timespans still reflected its sharp impact. The one‑year success ratio stood at 67%, three years at 79%, five years at 90%, and ten years at 100%. Since then, extending the dataset to December 2025 has added five more years of history, including the recovery from Covid, the Brexit aftermath and the Ukraine crisis. More recently, escalating US-China trade tensions and a broader rise in global tariffs have added another layer of uncertainty to markets. The updated figures show modest improvement: one‑year spans now succeed 69% of the time, three years 81%, five years 92%, while ten years remain at 100%.  

The bar chart below shows the success ratios have edged higher since 2020, with shorter horizons recovering from Covid’s impact while long horizons remain consistently positive.

The contrast is instructive. In 2020, short periods were still absorbing the pandemic shock, while longer periods had already smoothed it out. By 2025, the additional data confirms the same pattern but with slightly higher success ratios, highlighting that time continues to compress volatility. The lesson is consistent: turmoils leave scars in the short term, but the longer the period, the more certain the outcome.

Lessons Learnt: Exit & Re‑Entry in 2008

During the global financial crisis, Mobius withdrew fully to cash in 2008. The exit was well‑timed, but re‑entry proved harder: by the time consensus formed, prices had already risen. The FTSE outpaced Mobius in 2009, a lesson that shaped later decisions. Since then—through Brexit, Covid, and Ukraine—the club has remained invested, recognising that staying the course is often the wiser path. 

Monthly Valuations and Simplicity of Analysis

Mobius, like many UK clubs, values units monthly, usually on the last working day. This monthly cycle aligns with member contributions, participation, meetings and reviews, making monthly data the right length. Unlike daily‑priced funds, which require daily analysis and more complex calculations, clubs do not require that level of granularity. If we were analysing a daily‑priced fund, we would need to use daily returns to maintain validity, which would complicate calculations and dilute the clarity of the horizon‑based insights.  

Disclaimers: (1) the past is not necessarily a reliable guide for future returns. (2) This note does not offer any advice on investment or otherwise in the stock market. The report offers a reflection from the Mobius club’s perspective on the subject of “time in the market, not timing the market”.