I sold 200 ZEN that I bought for 8 dollars each when it rose to 30 dollars, and sold all when it reached 40 dollars.
Now ZEN has dropped below 30 dollars again, so I will first buy 100 at 29 dollars. If it continues to pull back to 24 dollars, I will buy another 50. If it pulls back below 20, I will buy 100 more. If it drops to 15 dollars, I will directly buy 200.