HONG KONG -- Hong Kong's two biggest share listings so far this year plunged on their trading debuts Thursday, in another blow for the city's weakest IPO market in a decade.

At the open, Chinese electric vehicle maker Zhejiang Leapmotor Technology tumbled nearly 15% from its initial 48 Hong Kong dollar price, while Onewo Space-Tech Service, Chinese developer Vanke's property services arm, dropped 7.5% from the shares' HK$45 initial pricing.