Combining 15 uncorrelated bets reduces risk by over 80 percent.

Test: whether combining 15 uncorrelated bets (zero pairwise correlation, comparable size and volatility, as the claim implies) cuts portfolio risk, measured as standard deviation of returns, by more than 80% compared with holding one such bet. Use standard portfolio math, where risk falls by 1 − 1/√N, or Dalio's/Bridgewater's published 'holy grail' diversification analysis on those assumptions. True: the reduction at 15 uncorrelated bets is over 80%. Mostly true: the principle holds and the reduction is close to but below 80% (about 74–80%), consistent with a rounded spoken figure. Mostly false: a large risk reduction occurs, but reaching over 80% needs assumptions the claim does not state (for example many more than 15 bets or negative correlations), or the reduction is well below 74%. False: combining 15 uncorrelated bets does not substantially reduce risk.

Set before the research began.

1. E1 Correlation and the Diversification Ratio: Formula, Worked Example, and Crisis Correlation Swoopr Investment

   “For any ρ below 1, the combined portfolio's volatility is mathematically guaranteed to fall below that weighted average, and the size of the reduction grows as ρ falls further toward -1.”

2. E2 Correlation and the Diversification Ratio: Formula, Worked Example, and Crisis Correlation Swoopr Investment

   “Holding more positions does not automatically mean more diversification; correlation structure matters more than position count.”

E1 supports the general principle that combining assets with correlation below 1 lowers portfolio volatility, and E2 notes that correlation structure is the key driver. Applying the standard formula named in the resolution criteria, risk falls by 1 − 1/√15. That is about 74%, which is a large reduction but short of the 'over 80 percent' stated. A figure in the 74–80% band fits the criteria's definition of mostly true: the principle holds, and the spoken number is somewhat overstated.