Brokers expect HSBC Holdings, a staple in the portfolios of Hongkongers, to see a large increase in interest from both local and international investors, as the stock’s minimum trading unit is set to change as part of the stock exchange’s board-lot reform process.Investors have long sought the change for the stock – known as a “widow and orphan” stock, as it pays a high dividend while bearing low risk – because its 400-share lot put it out of reach for many. At that level, retail investors had...