Christine Benz: Let's talk about exchange-traded funds. You've been critical of them in the past. You showed some data yesterday looking at turnover within ETFs. A lot of people use them for fast trading, and you've been critical of them mainly for that reason. It seems like maybe you're softening a little bit, that you think for a buy and hold investor, an ETF can work just fine, right?

John C. Bogle: I am softening a little bit. Can you imagine Bogle softening, but not in the way you suggest.

Benz: Oh, you're not getting soft. I'll say that.

Bogle: No, no; meaning that that kind of a consequence, investors trading and so on, the trading is the investor's enemy. Let me clear on that, and that's a fundamental principle of mine. Not in that way. It was at a Morningstar conference not so many years ago, maybe 25, when I said ETFs are like the famous Purdey shotgun--great for killing big game in Africa and great for suicide.

It all depends on what you want to do with the gun. I'm afraid there's too much trading in ETFs, but I also see that maybe I was too tough on the fact that there can be and is legitimate uses of ETFs.

Without the ETF, I think it's fair to say that robo-advisor industry, which is bringing costs down and using more technology--I hope not too much because that won't give the answer, either--but it's enabled that to be a business. It's enabled us to sell index funds in a lot of different venues very easily because you don't have the same registration problems.

They're listed securities that just trade, and there's a good side. As I say in the book, if an investor should try to figure out whether they want to own the Vanguard 500 traditional index fund, which I call a TIF, traditional index fund.

Benz: I like that.

Bogle: Nobody else does, so I appreciate that. The Vanguard ETF is an indifferent decision, ETF versus TIF. When you get any of this reverse leverage, all these games things, all the crazy, crazy new ETFs that are starting up--we have a vegan in ETF, I don't know what to do quite about that; I'm not a vegan, and I think there must be room for vegans, but the idea that stocks associated with veganism will somehow--veganism is, I guess, my word--it's opportunistic marketing.

Somebody wants to come in and make a lot of money at the expense of the investors who put their money in, because, don't forget the gross return on the market minus cost is the net return to the investor. Some of these pricings are very, very high, particularly relative to other ETFs.

Yes and no, but there are good uses of them. There's still an awful lot of evidence that the kind of funds that are brought into it are bad, and the way investors are using those funds are bad. You have this concentrating of the S&P 500 SPDR and other S&P 500 funds, it turns over I think 5,000 per cent a year, it's institutions trading money with one another. Is there anything the matter with that? I don't really see anything the matter with it, but does it have any social good? I don't see it has any, and it's a business that frankly bores me.