Edgar Cheng Wai-kin's three years as stock exchange chairman came to an end yesterday, after two of the most volatile weeks in Hong Kong's stock market life. Mr Cheng said the turmoil was the result of overseas factors and rising interest rates, and not a sign of problems within the Hong Kong exchange. He said trading was smooth, and that the exchange would keep monitoring brokers' financial positions. Mr Cheng leaves the exchange having proposed a bold set of reforms for the market and the exchange council in his last chairman's statement, contained in the exchange's annual report. He expects new council members to continue studying the reforms and is hopeful a new plan for the next three-to-five years will be ready by the end of the year. During his spell as chairman, Mr Cheng said he thought the exchange had improved its education of, and services to, brokers and listed companies. He will remain chairman of the steering committee of the Securities Institute which is a qualification examination for brokers, futures traders and fund managers. Hysan Development chairman Lee Hon-chiu is expected to be named his successor after a meeting on Monday morning.