The deal, which would quadruple Diamond's fleet of refined product carriers, will close in the third quarter. Diamond is buying the tankers from Cido Tanker Holding Co. The first delivery is scheduled for January.
Ross, founder of WL Ross & Co., said it's an "excellent time" to invest in the global shipping business.
"We have been looking for the right opportunity in the shipping industry for some time," Ross said in a statement.
Diamond S Shipping is based in Greenwich, Conn.