Palm oil king takes Whitehaven stake THE head of the world's largest processor of palm oil has emerged as a new shareholder on Whitehaven Coal's register following Nathan Tinkler's exit from the stock to pay down his significant debts. In a notice to the Australian Securities Exchange yesterday, Martua Sitorus, co-founder and chief operating officer of Singapore-listed Wilmar International, and companies associated with him, were revealed as holders of a 5.8 per cent stake in the company.