My mistake to part too soon

At one time, I expected Cisco would acquire ALU, so I bought it at $1. The 2B + 2B liability = 4B is a bargain considering it can build network and all the patents. Cisco missed the opportunity and I sold ALU with 40% profit in a few months. Then, ALU went on to a 3 or 4 bagger when it was acquired by another company. Cisco's fault and my fault to let go too soon. I forgot to use trailing stop as desribed in my book.