Shares in Ocean Rig, the most valuable asset of George Economou's DryShips, plunged Wednesday after the drilling contractor reported quarterly results that slightly missed expectations.

The rig and drillship owner's New York-listed shares dropped 22.2% to close the day at $1.12. DryShips, a bulker and offshore vessel owner, owns 40% of Ocean Rig.

Yesterday, Ocean Rig reported a fourth-quarter loss of $174m, reversing a $87.5m