George Economou's DryShips is buying more ships from its chief executive's private fleet.

The US-listed company has agreed to buy three modern newcastlemaxes and a 2010-built coated aframax for an aggregate purchase price of $198.5m.

The purchase includes existing financing in place and will be effected by way of stock purchase agreements and/or long-term bareboat charter parties with purchase obligations, DryShips said.