BEAT THE COUCH · THE FINE PRINT
Everything the game assumes, in one place. Where we had a choice, we made it in the trader's favor: if you lose to the couch here, you would have lost by more in real life.
24,668 daily closes of the S&P 500, from Jan 3, 1928 to Dec 31, 2025. That covers the 1929 crash, the Depression, the war, the long postwar bull, the 1970s, Black Monday, the dot-com bubble and bust, 2008, the COVID crash, the 2021 mania and the 2022 bear market. Before 1957 the index had 90 stocks, not 500; it is still the standard long series for large US companies.
Sources. Daily closes through 2019 are the Yahoo Finance ^GSPC series, cross-checked against an independent copy of the same series with no disagreements. 2020 to 2025 comes from stooq's daily S&P 500 series, joined to the older one at the end of 2019. Every year, including the joined ones, is then calibrated as below, so a seam cannot change any year's return.
The index itself ignores dividends, and for most of the 20th century dividends were a large share of the return. The game adds them back: each year's dividends are spread smoothly across that year's trading days, and every calendar year is scaled so it compounds to exactly the annual S&P 500 total return published by Aswath Damodaran at NYU Stern (to within a rounding error). Both you and the couch earn them. Day-to-day moves keep their real shape; only the yearly total is pinned.
Cash is not a mattress. While you are out of the market you earn that year's 3-month US Treasury bill return, from the same Damodaran table, accrued evenly day by day. That is worth real money in some decades: about 14% in 1981, near zero in the 1940s and the 2010s. In a few windows (1980 is the famous one) the T-bill alone beat the couch.
No commissions, no bid-ask spreads, no slippage, no taxes. Real traders pay all four, and short-term gains in the US can lose a large share to tax. Every press of the button is free and fills at the close. Every result in the game is the trader's best case.
?h=), so everyone who opens one plays the same two years. The classroom lesson and the archive use them.Your result is your final balance divided by the couch's, minus one. Then:
| Result | The stamp | On the ledger |
|---|---|---|
| No trades, in the market every day | ENLIGHTENED | couch |
| More than 2% ahead, monkeys beaten 90% or more | TIMED THE MARKET | skilled win |
| More than 2% ahead, monkeys beaten under 90% | LUCKY | lucky win |
| Ahead by 2% or less | DEAD HEAT | a win, column set by the audit |
| Behind by 2% or less | DEAD HEAT | couch |
| More than 2% behind | THE COUCH WINS | couch |
The 2% dead-heat band exists because two years of trading that ends within 2% of doing nothing is, for practical purposes, doing nothing. The stamp says so. The ledger still follows the money: finish a dollar ahead and it counts as a human win.
The 90th percentile rule comes from the monkey audit: 1,000 random schedules with your exact days in cash and number of trades, placed on random days. Beat 90% of them and the win counts as skill. The page has a live demo.
Every finished S&P 500 game files one anonymous row to the public ledger: the mode (random, daily, challenge), the window's start, the result against the couch, the number of trades, the time in the market, the monkey percentile, the stamp, and the dollars a losing player finished behind (the ledger calls them donations to the couch). No names, no emails. Replays of past daily hands are not filed. The bitcoin, gold and Apple couches keep separate books and never touch the main ledger. So far: 120,800 games, the couch ahead in 62%.
Bitcoin: 504 real six-hour candles from Bitstamp per round, from August 2011 to the end of 2025; one thin-book print in November 2011 was smoothed out, the real wild candles of 2013 were kept. Gold: two-year windows of the daily gold price from stooq, August 1971 to 2025. Apple: one-year windows of split- and dividend-adjusted daily prices from stooq, with the IPO years (December 1980 to 1984) from Yahoo Finance, joined at a fixed ratio. Cash earns the same T-bill rate on every couch.
The data is refreshed each January. Found an error? lucky@beatthecouch.com. The couch reads everything. Slowly.
PLAY THE COUCHnow that you have read the rules, which the couch never didYes. Both the player and the couch earn the S&P 500's total return: dividends are spread across each year's trading days so every calendar year compounds to the annual total return published by NYU Stern (Damodaran).
The 3-month US Treasury bill return for that year, accrued daily. In some years, such as 1980 and 1981, that was over 10%.
A finish within 2% of the couch, either way. Two years of trading that ends that close to doing nothing is stamped DEAD HEAT, though the ledger still counts any finish ahead of the couch as a human win.
No. Commissions, spreads, slippage and taxes are all ignored, which favors the trader. Every result is the trader's best case.
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Not financial advice. The couch is not licensed for anything.