Yup, there's a lot of great reading about the S&P 5 vs S&P 495.Maybe cap weighting like the S&P 500 index won't always perform so well.
With the concentration in weight of the top mega caps that just mostly doubled their valuation multiples, I wouldn't be comfortable with market cap indexing at this point.
For those who still want to use passive indexing solutions, I'd start looking at equal weighted like RSP and QQQE.
When reading about S&P 5 vs S&P 495, one interesting point is that fund managers can't afford to exit their positions on the S&P 5 stocks because they are currently the very best performers, so they have to ride that momentum... until it reaches the peak and then they try to time the market right before the bubble pops.
What happens to market cap indexing when the momentum is on those mega caps? Pretty scary for those passive investors.