Switzerland-based oil trader Vitol’s investment arm has acquired the 50 percent stake it did not already own in refiner VTTI BV for $830 million to expand its asset base. Vitol’s unit, Vitol Investment Partnership, bought the stake from Malaysian shipping company MISC Bhd, VTTI’s limited partnership, VTTI Energy Partners LP, said on Friday. VTTI Energy Partners said VTTI would continue to operate independently under Chief Executive Rob Nijst. VTTI has total gross storage capacity of 54 million barrels, including assets under construction, the company said.