No, you don't. You bury it in the 'sank gradually' part: [...] You can get an abrupt pop inside an normal-looking beginning/end comparison if something compensates for the pop, like another rise (unlikely) or prices then falling slower than they normally would ('gradually'). The ground lost in the pop is then made up later.

Ohh, I see what you're getting at. I'd interpreted "compensation" more narrowly as something halting or outright reversing the fall in prices, not merely decelerating it.

Yeah, my scenario implies an unusually slow price drop after the initial speedy crash. That wouldn't surprise me in the wake of the unravelling of a self-fulfilling speculative mania.

It's the topic of chapter 5, "The Bubonic Plague". [...] (It's on Libgen, and isn't a very long book.)

Good to know, thanks. Added that to my mental things-to-look-at-on-a-rainy-day list.