#MARKETS & INVESTING
'The stock market is a casino' comes up every time markets fall. The two actually run on opposite mechanics — written into law for one, measured over 125 years for the other.
Published on August 23, 2026
In France, the decree of 29 July 2009 on casino gaming regulations sets a maximum player return rate of 85% on slot machines: by legal construction, the casino keeps at least 15% of what's wagered, on average, over time. In practice, most venues pay out between 88% and 98% depending on the machine, and roulette carries a smaller house edge (2.7% on European roulette, down to 1.35% on French roulette with the 'en prison' rule). Either way, the player's expected return is negative from the very first bet: that's a rule of the game, not an accident. By contrast, according to Dimson, Marsh & Staunton (UBS Global Investment Returns Yearbook), world equities have returned an average of 6.6% per year above inflation since 1900 — 125 years of data — a positive average return, though neither guaranteed nor linear from one year to the next.
Do a casino bet and a stock market investment carry the same expected return?
No: the player return rate is capped by law in a way that guarantees the casino an average gain, while equities have delivered, on average and over the long run, a positive real return — without that guaranteeing an outcome over any short period or for any individual investor.
In other words: playing at a casino means betting against rules built by design to make the player lose on average; investing in equities means betting on economic growth, with no individual guarantee but a favorable long-run historical average.
Three caveats, because they matter
- The player return rate is a payout rate per bet or per session, not an annualized return: the two figures aren't expressed in the same unit and don't compare term for term.
- Equity returns are neither guaranteed nor linear: over several consecutive years, an investor can lose money (2000-2002, 2008), whereas at a casino, the player's average loss is locked in from the first bet.
- The 6.6% figure is a 125-year world average that smooths over large disparities between countries and periods; a real investor also faces fees, taxes, and the order in which returns occur, none of which the historical average captures.
Why it still matters: equating the stock market with a casino ignores a structural difference: one is built by regulatory design to make the player lose on average, the other has historically rewarded economic risk-taking over the long run — neither guarantees an individual short-term outcome.
For you
- Does this comparison still hold if you limit it to a few months instead of 125 years of data?
- Is a slot machine's player return rate always displayed before you play?
Source: Decree of 29 July 2009 on casino gaming regulations, art. 13 (Légifrance, France); Dimson, Marsh & Staunton, UBS Global Investment Returns Yearbook 2026.
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