A rush of Chinese tech companies has applied for initial public offerings in Hong Kong after the city changed confidential filing rules as part of reforms that have helped fuel a listing boom in the territory.

Regulators in May announced a confidential filing option for lossmaking technology and biotechnology companies. Such filings allow companies to have their financial and operational information reviewed by the exchange and regulators before they publicly reveal their intention to float.

Biren Technology, one of China’s leading chipmakers, made a confidential filing in recent weeks, according to two people with knowledge of the matter. Rival Enflame Technology and artificial intelligence start-up Zhipu, which was valued at more than $5bn in a private funding round earlier this year, also plan to submit soon, the people said.