HONG KONG (Reuters) - The chief executive of Hong Kong's stock exchange, Charles Li, will step down at his own request at the end of 2020, sooner than expected, the company said an exchange filing on Tuesday (Sept 29).

Calvin Tai, the chief operating officer of Hong Kong Exchanges and Clearing (HKEX) will serve as interim chief executive from Jan 1, 2021.

In May, HKEX said Li would step down as chief executive when his term ended in October 2021, or earlier if a suitable successor was found.

That has yet to happen, but HKEX chairman Laura Cha, who is leading the committee to find the next CEO, said in a statement it was making "good progress" and would update the market when appropriate.

Li, who became HKEX CEO in 2010, will be a senior advisor to the HKEX board for six months after stepping down, the company said.

"Given the strength of our business as well as our markets, it is now the right time for me to begin to pass the mantle to the next generation of HKEX leaders," Li said in the statement issued after the market close.

Tai is an HKEX longtimer who joined the Hong Kong Futures Exchange in 1998, prior to its 2000 merger with the Hong Kong Stock Exchange that created HKEX.

During his time as CEO, Li built ties with Chinese mainland markets, attracted major companies to the bourse and oversaw the 2012 acquisition of the London Metal Exchange, although last year's failed bid for the London Stock Exchange removed some of the gloss from his 10-year reign.

Next month, Alibaba Group's fintech arm Ant Group aims to raise about US$17.5 billion in the Hong Kong leg of its US$35 billion dual listing, Reuters reported last week. The IPO, which is shared with Shanghai's STAR Market, could be the world's largest.