I don't think there any company that does the job of monitoring stolen coin because despite the transactions in bitcoin blockchain being viewable by anyone. It's also a little easy to create new addresses and also mix stolen bitcoins through bitcoin mixers making it hard for someone who's trying to trace the stolen coins.
there are a lot of these "companies" that claim to be doing that, they are called "blockchain analyzers", there are at least a couple of dozens of them around with new ones being created regularly!
to this day i have never seen any of them play a major role in catching any of the hackers. they either go uncaught or the law enforcement catches them when they do things such as using the same coins to send to their verified coinbase account or something like that.