PT Adaro Energy, Southeast Asia’s best-performing stock this year, is expected by analysts to extend gains in 2017 as it benefits from rising coal prices and cost-cutting initiatives. The coal miner’s measures to reduce expenses resulted in an earnings before interest, taxes, depreciation and amortization margin of 36.2 percent in the third quarter, the largest among Indonesia’s five biggest listed coal miners, and the highest quarterly reading in three years, according to data compiled by Bloomberg.