While I was debugging an algorithm I noticed a stock (MTW) took a huge loss on March 04, 2016. According to this article the reason for the apparent crash was that the company completed a spinoff of its food service with new ticker (MFS, now WBT), and "shareholders of the original company got one share of the new company for each share they'd owned of the old one". However when I checked my holdings I had neither MFS nor WBT.