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.)