Xiaomi Corp. shares had their biggest intraday gain in three weeks in Hong Kong after the maker of smartphones and gadgets unveiled a HK$10 billion ($1.72 billion) stock-buyback plan.

The board approved a mandate for the Chinese manufacturer to repurchase shares in the open market for as much as that amount, according to an exchange filing late Thursday. The stock added as much as 9.8% and was up 8% at 9.44am local time.

The company said repurchases will demonstrate its confidence in its business outlook. Xiaomi is among smartphone makers trying to grab market share expected to be vacated by Huawei Technologies Co., which no longer has access to key chipmaking suppliers owing to U.S. sanctions.

Xiaomi started the year with the launch of a new flagship smartphone, the Mi 11, one of the first to adopt Qualcomm's latest processor and a big advance for the company in camera performance. In January, it ranked a close second to Oppo with 20% of the Chinese smartphone market, capturing much of the online clientele that Huawei has been losing, according to Counterpoint Research.