Cathay Pacific Airways Ltd. is losing its decades-old membership of Hong Kong’s benchmark equity gauge as the city’s flagship carrier struggles to revive earnings. The airline, in which Qatar Airways Ltd. just acquired a stake, will be dropped along with Kunlun Energy Co. as part of Hang Seng Indexes Co.’s quarterly review. Country Garden Holdings Co., a Chinese property developer, and Sunny Optical Technology Group Co., an Apple Inc. supplier, will replace them on the 50-strong measure, effective Dec. 4, according to an announcement by the index compiler. The deletion is the latest blow for Cathay Pacific, founded in 1946, after it was removed from MSCI Inc.’s Hong Kong index in May. The airline has lost almost half its market valuation in the past seven years as the carrier battled rising competition from Chinese rivals as well as suffering ill-judged fuel hedges. Rupert Hogg, who took over as chief executive officer this year, has been seeking to cut costs after the airline posted its biggest half-yearly loss in at least two decades. Hong Kong conglomerate Swire Pacific Ltd., is the largest shareholder of Cathay Pacific with about 45 percent. Qatar Airways said on Monday it will buy 9.6 percent of the airline from Hong Kong-based Kingboard Chemical Holdings Ltd. and related companies for HK$5.16 billion ($662 million). Country Garden and Sunny Optical have more than doubled in the past 12 months, compared with the Hang Seng Index’s 28 percent gain. Separately, Guangzhou Automobile Group Co. will be added to the Hang Seng China Enterprises Index, at the expense of China Longyuan Power Group Corp, according to the index compiler.