Subject: Re: Bogle , back to the real world,
But the thing about the SPY is that the top firms are very heavily weighted - right now, the top 20 firms are worth about as much as the other 480 firms combined. So the whole question becomes, do those top 20 firms tend to have good returns, or not? If the answer is no, as much research indicates, then you don't want to be overweight those top 20 firms...

I might add, "even if the answer is no idea, you don't want to overweight those firms".

Why overweight anything without decent evidence it's likely to outperform or less likely to do badly? Company specific risk can strike at random. Possibly more so in this era.

Jim