Hoban Group's stake in Hanjin KAL has gained an estimated 883 billion won ($657 million) in market value since the beginning of this week, as the construction group's emergence as the holding company's largest shareholder has fueled speculation over a potential battle for control. The valuation gain follows Wednesday's disclosure that Hoban and related parties held 13,814,053 common shares, or 20.69 percent of Hanjin KAL, narrowly overtaking Hanjin Group Chairman Cho Won-tae and his cohort, whose combined stake stood at 20.58 percent. Hanjin KAL shares closed at 123,900 won last Friday before climbing to 187,800 won Thursday morning, a gain of 63,900 won, or approximately 51.6 percent. Applying the increase to Hoban's disclosed shareholding translates into a valuation gain of approximately 882.7 billion won. At Thursday morning's price, its stake was worth about 2.59 trillion won, up from approximately 1.71 trillion won at Friday's close. Investor interest intensified after reports emerged Monday that Hoban had filed a business combination notification with the Fair Trade Commission. Ch