pandemic housing boom has attracted a larger-than-usual share of speculators, many of whom took advantage of falling variable mortgage rates to take out multiple loans, but the central bank’s surprise warning this week about an early interest rate lift-off could douse a rally fueled by cheap debt.Earlier and faster rate hikes could trigger higher payments for many of these buyers, and investors with multiple properties could respond by selling some of them into ebbing demand if their commitments become too onerous.Already, the housing market has started to cool as fixed rate mortgages rose 60 basis points on average this year, according to Ratehub.ca, tracking rising bond yields.