A fleet of supertankers carrying Saudi oil will add to the growing congestion at U.S. ports in coming weeks at the same time producers are shutting in output as they run out of space to store unwanted supplies.

The Saudi Arabian Oil Company, the most profitable commercial enterprise in the world, started trading shares on Wednesday, a week after its long-awaited listing on the Saudi Arabian stock exchange broke the record as the largest initial public offering (IPO) in history.