[nilkn]

I'm very curious about this as well. This is the main thing that has held me back from a meaningful rebalancing. Eating a huge tax bill to avoid a theoretical future loss of unknown size and duration while also losing out on potential gains if that loss ends up not materializing is a hard pill to swallow. I suppose this is probably why most long-term investment advice suggests not trying to time the market unless you have a very short time horizon. (Note: for me, I'm referring to funds in taxable brokerage accounts.)

[alsetmusic]

I have a family member who once told me that their net worth was roughly halved in 2008. They probably recovered it if they stayed in the market after, but I don't know what they did.

I suppose the real question is whether you can weather the storm long enough for the market to recover. And beyond that, how cynical you are overall about everything taking completely before that can happen. I wonder a lot about that second one.

[nilkn]

If you'd been DCAing a fixed amount monthly into stocks for 10 years prior to the 2007 peak, then during the crash continued doing so without selling, the total value of your portfolio would've matched its pre-cash peak in just 3 years and exceeded it significantly by the time the market itself recovered in ~5.5 years.

3 years is really not a long time. So I'd say it comes down to emotional fortitude and probability of staying employed. If your time horizon is longer than 3 years, the calculation of whether to sell should essentially come down to calculating your odds of keeping your job. I bet it's possible to build a robust mathematical model that recommends a decision given your best personal estimate of your layoff probability during a severe market crash.