Time lag moving out of shares ISA. Dangerous?

grey_gym_sock

well, this is how pricing of funds works - you have to deal "blind". you can usually limit the uncertainty to a few hours, e.g. if a fund is priced at noon, your platform may accept instructions a few hours earlier. although the most recent price you'll know for the fund will be from the previous day, you can get a rough idea of where it is likely to be now by looking at a relevant index - e.g. if it invests in big UK shares, look at how the FTSE 100 has moved since noon yesterday.

while this "forward pricing" can be a nuisance, the reality is that it rarely matters. i think you do have the right idea, that it would be a bad time to sell just after a crash. but that is very rare.