If we measure a bank in terms of the total assets it owns, HSBC is the largest in Europe. Its services and subsidiaries span more than 60 nations, and it serves 39 million customers. HSBC has been known to sponsor various motor sports and golf tournaments and is an official partner of the Wimbledon Championships. For quite a while now, this London-headquartered bank has set its sights on advertising extensively at airports. But why exactly is this the case?