Chinese electric vehicle (EV) maker Zhejiang Leapmotor Technology's shares opened at HK$41 ($5.22) apiece, down 14.5% from their IPO offering price of HK$48.
The stock then plunged to $HK34.
Shares of Onewo Inc, the property services arm of developer China Vanke Co Ltd, fell more than 7% at open from their IPO price HK$49.35.
Hong Kong's Hang Seng Index opened nearly 2% higher.
($1 = 7.8498 Hong Kong dollars)
(Reporting by Scott Murdoch; Editing by Himani Sarkar)