-The story Of The Titanic-
So scientifically had this great sailing ship been constructed, with 16 watertight compartments in a 1/6 mile long hull, that the captain had made a pre-voyage boast, "Not even God himself could sink her". The builders had calculated that even if four of the compartments should burst, the ship would still float! But on that starry night, six of them exploded and began to suck in the frigid water of the North Atlantic! Mathematically, the "unsinkable ship" was mortally wounded. And, in two hours she was gone. Commander Lightoller, one of the few crew members who survived the tragedy, described the moment she sank.
I consider the Titanic to be an example of a black swan. You can never be overly confident that a stock you own will never "sink" It's best to take profits when your stock starts exploring some new territory. You never know if its going to hit that iceberg.