A 32% rally this year has catapulted HSBC Holdings Plc’s shares to their highest level in four years, with improving margins potentially providing further support for the stock.

Better net interest margin due to a rebound in Hibor — Hong Kong’s interbank lending rates — as well as expectations for further share buybacks have helped boost investor sentiment, analysts said. The bank announced a $2 billion share buyback plan and resumed paying quarterly dividends in May.