I significantly increased my investments in the last 2 months so i am down about 6% on investments YTD. But now is the worst possible time to sell . I'll just keep investing based in my plan - investing each month in diversified ETFs, and a local bias. The strategy has already worked as hoped, because not being 100% in on US stocks has softened some of the blow.
In every scenario, if your portfolio was properly designed and diversified then not crystalizing losses by trying to time the market is the best strategy. If you are investing regularly then you will gain from Dollar Cost Averaging, i.e. you will gain from buying lower priced stocks during the downturn.
To be clear, I won't be looking to cash out for 10+ years and even that is long before retirement.