Question: Right after the event, I felt shocked and depressed. I've been engaging in stocks for about a year now but I've never encountered such a big jump in such a short time. What I'm planning to do is just wait for it to rise again, which I'm not sure when. (Well, who is?)

**What should my mindset be?** 

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I understand that there are already lots of questions regarding **When should I sell?** or **Should I set a stop loss?** For me, this question is not 100% about how to protect your money, but it's more of **In extreme cases like this, how should I mentally prepare myself?**

I anticipate that there will be comments/answers like "we can't give advice if we don't know the exact stock in topic" or somewhere along those lines. I want to pre-emptively tackle this and say that this question is not only for my specific current case. I'd prefer answers to be generic for everyone facing the same problem.

Answer: 
From some of your previous questions it seems like you trade quite often, so I am assuming you are not a "Buy and Hold" person. If that is the case, then have you got a written Trading Plan? Considering you don't know what to do after a 40% drop, I assume the answer to this is that you don't have a Trading Plan.

Before you enter any trade you should have your exit point for that trade pre-determined, and this should be included in your Trading Plan. You should also include how you pick the shares you buy, do you use fundamental analysis, technical analysis, a combination of the two, a dart board or some kind of advisory service? Then finally and most importantly you should have your position sizing and risk management incorporated into your Plan.

If you are doing all this, and had automatic stop loss orders placed when you entered your buy orders, then you would have been out of the stock well before your loss got to 40%.

If you are looking to hang on and hoping for the stock to recover, remember with a 40% drop, the stock will now need to rise by 67% just for you to break even on the trade. Even if the stock did recover, how long would it take? There is the potential for opportunity loss waiting for this stock to recover, and that might take years. If the stock has fallen by 40% in a short time it is most likely that it will continue to fall in the short term, and if it falls to 50%, then the recovery would need to be 100% just for you to break even.

Leave your emotions out of your trading as much as possible, have a written Trading Plan which incorporates your risk management. A good book to read on the psychology of the markets, position sizing and risk management is "Trade your way to Financial Freedom" by Van Tharp (I actually went to see him talk tonight in Sydney, all the way over from the USA).
The mental approach should be that you always knew the risk of gambling and it was extra money that you had (or should have had). Now think that the 'horse' race is not over and in the near future it will pick up pace against the others and be back on track.