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: 
Have the reasons you originally purchased the stock changed? Is the company still sound? Does the company have a new competitor? Has the company changed the way they operate?

If the company is the same, except for stock price, why would you change your mind on the company now?

ESPECIALLY if the company has not changed, -- but only other people's PERCEPTION of the company, then your original reasons for buying it are still valid. 

In fact, if you are not a day-trader, then this COMPANY JUST WENT ON SALE and you should buy more.

If you are a day trader, then you do care about the herd's perception of value (not true value) and you should sell.

DAY TRADER = SELL

BUY AND HOLD (WITH INTELLIGENT RESEARCH) = BUY MORE
Hopefully, before you invested in this stock, you evaluated the company. You looked at the financial information about the company and where the company was headed, and evaluated whether the stock was undervalued or overvalued. Hopefully, you determined that the stock was undervalued at the time you bought it.

The thing to do now is to reevaluate the stock. Do you think the stock is overvalued or undervalued right now? If you didn't own it, would you buy it today? Instead of looking at the past performance of the stock, you want to try to determine which direction the stock will go from today. If you wouldn't buy it today at it's current price, then you should sell.

If you have no idea how to do this evaluation, neither do I. For me, with the investing knowledge I have right now, investing in an individual stock would be way too risky. If you don't know how to evaluate a stock and determine if it is a good buy or not, then you should stay away from individual stocks and instead invest in stock mutual funds, which lower the risk by diversifying over lots of stocks.