Kingboard Laminates Holdings (01888) fell 5.4% to HK$43.86, while Yangtze Optical Fibre and Cable (06869) dropped 4.4% to HK$159.3, according to ETNet.

The moves came even after Nvidia said it would invest $3.5 billion in MediaTek through the purchase of convertible bonds and deepen technical cooperation to improve data transmission between components in data centres. Nvidia shares rose 1.4% overnight.

ETNet reported that Hong Kong AI hardware stocks had already posted strong gains in August on speculative buying, with Kingboard Laminates up 57.6% for the month and Yangtze Optical Fibre and Cable up 72.3%. On the first trading day of September, both stocks gave back some of those gains.

The Hang Seng Index was down 0.8% at 25,358, the Hang Seng China Enterprises Index fell 0.5% to 8,473, and the Hang Seng Tech Index slipped 0.6% to 4,594. Mainboard turnover was about HK$53.3 billion.