The VLCCs follow an order for two 320,000-dwt tankers at the Japanese yard that were contracted in October at $97m each for delivery positions in 2016.
Fredriksen has been a key customer at JMU, where he is also building two capesizes and a pair of supramax bulkers.
The JMU VLCC berths come on top of a pair of firm VLCCs, plus two optional vessels, which Fredriksen secured at Hyundai Heavy Industries in the past few weeks.
