This summer, when Hong Kong’s stock market rout seemed to have no end in sight, the city’s financial chief, Paul Chan, jumped into action, creating a task force to inject confidence into a market that was being pummeled by global investors wary of China.

Hong Kong cut taxes on trading and Mr. Chan went on a roadshow to Europe and the United States, promising measures to “let investors feel optimistic about the outlook.” Investors were anything but sanguine, however, and the city’s Hang Seng Exchange is among the world’s worst-performing stock markets this year.

The Hang Seng Index finished Friday, its last trading day in 2023, 14 percent lower than it started the year. Stocks in mainland China also recorded losses this year, with the CSI 300, an index that tracks companies listed in Shanghai and Shenzhen, declining 11 percent.

Hundreds of billions of dollars flowed out this year as money managers and pension funds reduced their holdings in Hong Kong, which has long been a gateway for foreign investors wanting to put money into mainland China. The outflows were largely driven by an economic downturn in China and mounting pressure on American investors to sell their exposure to Chinese companies.