CANADA'S reputation for financial regulation is starry. Its banks got through the crisis unscathed. According to Moody's, a ratings agency, Royal Bank of Canada sits alongside HSBC and JPMorgan Chase in the top tier of global banks. And Canadian policymakers are old hands at pulling “macroprudential” levers of the sort now in vogue among rich-world central banks.

But questions still nag. Some say that Canada's banks are flattered by a huge indemnity offered by Canada Mortgage and Housing Corp (CMHC), a public institution that insures mortgages with a loan-to-value ratio of more than 80%. CHMC's book grew to C$567 billion ($557 billion) in 2011, up from C$345 billion four years earlier. And Canada's housing market looks very frothy on some measures: The Economist's analysis of price-to-rent ratios suggests that Canadian properties were about 75% above their long-run “fair value” in the first quarter of 2012 (see chart). Although less than 0.5% of CHMC's mortgages are in arrears, such exuberance is a worry. The central bank recently labelled housing as “the most important domestic risk to financial stability in Canada”.