Maersk Line, known as the world's largest container shipping company, has teamed up with IBM to start using blockchain to track its cargo. From the time the tech titan opened its Watson-powered blockchain service to enterprise customers last year, it has already signed up over 400 clients, including Walmart. It helps companies use blockchain -- a digital leader that logs transactions that can't be modified later -- in different ways, not just for financial transactions. For Maersk, it's to give buyers, sellers and customs officials a way to keep track of the goods it hauls as they make their way across the globe. Everybody involved can check where the shipment is at any point.