Shares in China's two dominant mobile operators were hard hit on Wednesday, with HK$15.6 billion in market capitalisation erased on renewed concerns about competition and regulatory risk. China Mobile (Hong Kong), down 4.15 per cent, and rival China Unicom, down 3.13 per cent, were the top losers among the 33 Hang Seng Index stocks. China Mobile shares plunged to as low as HK$15.90 in the afternoon before bouncing back to HK$16.15, down 70 HK cents - the stock's lowest close since April 15, 1999. With HK$830 million worth of shares changing hands, it accounted for about 13.5 per cent of Wednesday's HK$6.11 billion turnover. The volume was about 2.6 times its average. Vodafone Group, which holds 2.5 per cent of China Mobile, eased concern that it might sell China Mobile shares. 'We're committed for the long-term to relations with China Mobile. Our chief executive sits on the [China Mobile] board,' a Vodafone spokesman said.