Do you think it's going down from here or up from here?
If you think it's going down, how far? To $100 (75% loss from 400)? To $50?
What percentage loss can you stomach?
If you think it's going up, take the opportunity to buy it on sale.
I think the financial markets are some of the only places where we lose perspective of what it means to buy and own things.
If you buy a smartphone today for $600 and next month it's $300, do you sell your phone? No, you buy your spouse one too at the better $300 price.
There are plenty of things right now all around you losing value every day that you own. Simply depreciating because of time. But because we don't see their values going down on a ticker or chart, we don't panic.
Own it if you feel like it's good to own it and that it will return you value well into the future.