The head of Hong Kong's securities watchdog has brushed aside US President Donald Trump's painting a bleak picture of the city's financial market performance on the world stage following the United States' decision to strip the special administrative region of its special economic status.

Hong Kong's full-fledged standing as an international financial center is here to stay and will buck the global economy's downward trend with the Chinese mainland's resolute support and the SAR's long-standing competitive edge, said Tim Lui Tim-leung, chairman of the Securities and Futures Commission.

Trump had said on Wednesday Hong Kong will "no longer be a successful exchange" after losing its special economic status, but Lui said he disagreed with that doomsday talk.

"People should have confidence in Hong Kong's stock market. If we look at our stock exchange and our clearing house, they've all been functioning very well even during the most turbulent time recently," he said.

Lui said Hong Kong's reputation as a global financial hub is built on years of hard work and contributions from various sectors. With all the criteria to remain as a "full-fledged" international financial center, the city's time-honored competitive edge in the business sector will not be gone overnight.

Apart from Hong Kong's well-established legal system, it has a solid infrastructure, a sound banking system, free flow of capital, low tax rates, and a highly regarded regulatory regime, he explained.

The SFC chief said he is confident about Hong Kong's future prospects with the influx of capital from the Chinese mainland, as well as Western countries.

In June, mainland tech behemoths, Nasdaq-listed JD and NetEase, raised a total of US$6.6 billion through secondary listings on the Hong Kong Stock Exchange amid growing US hostility against Chinese enterprises.