[fitchjo]

Not sure I follow your logic: 1. What are you calling the market in your first sentence? 2. Why/how is an index fund somehow less risky? What is the fund indexing and how does that compare to the market in your first sentence?

In your scenario, if the index fund is properly designed to capture the risk of the "market" as you have defined it, a monkey has equal chance of performing better or worse than the index fund and the average monkey (or an average of a large enough set of monkeys) will perform with the index fund. Certainly, though, if your index fund is not designed to be reflective of the market, but of some subset, then it will carry different risk, but not necessarily less risk. However, a monkey randomly picking stocks from a pool will not, on average, outperform the average return of that pool of stocks.

[jjoonathan]

An index fund is more likely to invest in BoringBigCo than NewShinyCo. The monkey is equally likely to invest in BoringBigCo and NewShinyCo. The latter strategy has more risk.