Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

One of my stocks dropped 40% in 2 days, how should I mentally approach this?
You bought the stock at some point in the past. You must have had a reason for this purchase. Has the recent change in price changed the reason you bought the stock? You must assume your losses are sunk costs. No matter what action you take, you can not recover your losses. Do not attempt to hold the stock in the hopes of regaining value, or sell it to stop losses. Instead approach this event as if this very day, you were given shares of the company's stock at their current market value for free as a gift. In this hypothetical situation, would you hold the shares, or sell them? Use that to judge your options. Not everyone, myself included, can handle the mental stress of watching share prices change. You can always consider trading index funds instead, which are much less volatile but will provide consistent, albeit, boring returns. This may or may not be you, but it's an option. Finally, do not keep money in the market you are not prepared to lose. It seems obvious, but if you lost 40% today, you could lose 100% tomorrow.