He says he's (reluctantly) doing active stock picking. He's a professional investor; I'm just some software engineer with a nest egg, which is 100% in index funds today. What should I be doing, as a schmoe who wants to save money?
1. Even among index funds, maintain some diversification. Don't put all in US large caps (S&P 500), but also some international and some small caps (Russel 2000).
He is saying that given how much money is invested via index funds now, there are opportunities in assets that are not (or insufficiently) represented in index funds. (This is hard, though, and the standard advice to refrain from trying and placing your bets on index funds instead remains valid, I think, particularly for mature markets in which you don't have an edge.)
The second take-away is at a tension with the first:
2. Avoid ETFs that handle illiquid assets (real estate, bonds, etc.) or create synthetic exposure using swaps and derivatives.
For big, liquid assets, the ETF or index fund can just take the investor money and go buy the assets. Then the value of the fund is approximately the value of its constituent assets, sort of by definition, and that value is relatively easy to realise (that is, if you want your money back, you get it - they'll have to sell some of the assets, but they're liquid, and that won't influence price too much).
For smaller or more exotic assets, a fund might not buy them outright, but contract with a third party (an investment bank, typically), and give the bank the money, with the bank promising that it will return the value of the asset. So, it's "like" holding the asset, except that you get the credit risk of the bank - there's a risk the bank might not be able to uphold its promise. And this is most likely to happen when everyone runs for the exit.
> The theater keeps getting more crowded, but the exit door is the same as it always was. All this gets worse as you get into even less liquid equity and bond markets globally.
> ... the impossibility of unwinding the derivatives and naked buy/sell strategies used to help so many of these funds pseudo-match flows and prices each and every day.
So, an ETF promising to deliver the value of an index can generally do it, and there was no big failure so far, but scenarios are conceivable where it cannot deliver.