Shares in China Mobile (Hong Kong), the mainland’s largest mobile supplier, fell 10.5% to HK$35.90. China Unicom, the second largest operator, fell 11% to HK$10.05.

The falls were prompted by the announcement of tariff changes that market insiders believe will lower the companies’ revenues by between five and 10%. Hong Kong’s benchmark Hang Seng index ended down nearly 3% to 13,966.43 – its lowest levels since May last year.

Similarly to other industry giants, China Mobile’s value has shed nearly 21% over the past month and is trading at half its peak price last year.