Joining the index means they will have access to passive inflows from those ETFs that track the index.
Xpeng and Li Auto have been included in the Hang Seng Tech Index, which will be effective from Monday, March 7.
Hang Seng Indexes Company today announced the results of its fourth quarterly review showing the change.
Xpeng, Li Auto, and artificial intelligence company SenseTime, are the latest companies to join the Hang Seng Tech Index, while Tongcheng Travel Holdings, Weimob and Autohome have been removed.
Joining the index means they will have access to passive inflows from those ETFs that track the index.
But Hong Kong stocks have performed poorly recently, with the Hang Seng Tech Index down 48 percent in the past year.
Xpeng, which listed in Hong Kong on July 7 last year, is down 7.7 percent so far. Li Auto, which listed in Hong Kong on August 12 last year, is down 1.8 percent so far.
On February 9, the Shenzhen Stock Exchange announced that it had adjusted the list of Hong Kong-Mainland Stock Connect stocks to include Xpeng shares traded in Hong Kong.
The stock connect mechanism was launched in November 2014 to facilitate investors from Hong Kong and the mainland to buy each other's stocks.
With the inclusion in the list, Chinese mainland investors will be able to trade their stocks more easily, although investors with securities account assets of more than RMB 500,000 will only be eligible to participate in the facility.
Li Auto is also expected to be included in the mechanism in March.