HSBC's move to ditch its 45-floor Canary Wharf tower in favour of a much smaller development in central London is one of the most visible examples yet of an office downsizing trend that's rocking commercial real estate markets globally. Europe's largest bank told staff on Monday that it planned to quit the skyscraper that bears its name in the east London financial district and move some 8,000 workers to a redeveloped office complex overlooking St Paul's Cathedral. A recent spate of downsizing moves by major employers comes as landlords and real estate developers already face a crunch from soaring financing costs, adding to pressure on the sector.