I very much enjoyed the quote. I've been meaning to read that book for a long time, but haven't gotten around to it.

But I'm not entirely sure that the writer of the post necessarily understood what Old Turkey was saying. Maybe so, maybe not. The writer takes it to mean HODL: buy and hold your equities forever.

But maybe Old Turkey meant his comment more literally. For example, perhaps just a few months or years later, his answer would have changed to "It's not bull market any more". Which may well have been true.

There is a certain school of thought that how one invests might reasonably change based on whether it is, or is not, an ongoing bull market. For example, during a bull market, there is simply no point in holding anything other than a broad index a la Bogle. It would be wasted effort, and would only increase your fees, tax, and stress. A bull market is normally years long.

But when it's not a bull market, especially if it's no longer a bull market but valuations are still high, then one has a finite number of choices. Live with low returns for maybe a long while; skip the index: be discerning in your portfolio selections to avoid things which are themselves still at bubbly valuations, or chosen on some other criteria you deem sensible; invest in things other than the stock market; or try your hand at varying your ownership based on the pricing or (if you dare) timing of the securities involved.

A bull market is pretty much by definition a market going up in price: you'll be seeing see periodic fresh market highs without huge time gaps between them. Consequently I use a simple test for whether or not one is demonstrably still in a bull market: if a fresh recent high was seen in the last while, you are (so be a Boglehead if you like). If not, then perhaps you aren't in a bull market (so be more judicious). I would not use this as a market timing signal, but I do keep an eye on such things to know which "regime" we seem to be in. As we just had a fresh all time market high, it's definitely a bull market at the moment. Monday I'll be allocating a little capital to a "roll your own index" approach. Since 2000, if the trailing 6-month index high was bumped higher any time in the last six months, call that day part of an ongoing bull market. Real total return from the S&P 500 during those days was inflation + 9.15%/year rate, 76% of the time. The rest of the time, the S&P return was inflation - 8.25%/year. It's not a reliable omen, but it seems not to be entirely random either.

Jim