The visit was Mr. Bannon’s first high-profile overseas trip since he left the White House in August and returned to Breitbart News, the right-wing news outlet.

CLSA would not say whether it had paid Mr. Bannon for his appearance. “CLSA does not discuss any agreements that we might have with speakers,” said Simone Wheeler, a spokeswoman for the firm.

Over lunch in a private room at the Grissini restaurant in the Grand Hyatt hotel, overlooking Victoria Harbour, Mr. Bannon shared his insights on a range of topics — including the United States electoral system, immigration and the escalating conflict over North Korea — with a small group of investors, according to two people who were in attendance.

The event was organized by CLSA for important clients of its brokerage business.

During the lunch, which lasted more than an hour, Mr. Bannon told the group that Mr. Trump had great respect for Mr. Xi and felt that the two leaders could find a solution to the North Korea crisis, according to the two investors in attendance, who spoke on the condition of anonymity because they were not authorized to speak publicly.

In his keynote address, in a crowded Grand Hyatt ballroom, Mr. Bannon discussed economic nationalism in the United States and its spread across the globe, including in Britain. He called the U.K. Independence Party, which pushed successfully last year for Britain’s exit from the European Union, a professional version of the Tea Party movement in the United States, according to one audience member. The address was closed to the news media.