Is it time to worry that the boom in global megacity housing prices could turn into a bust with a potential contagion across the global economy?

This is a bit old but at the time it was published the timing was off.
Now, with property price news from London and Sydney sounding a bit gloomy it might be time.
From 13D Research, June 7, 2018:

A pattern of weakness is becoming apparent in megacity housing markets around the world. By the end of May, home prices in Sidney had fallen 4.7% year-over-year. In Toronto, the average price of a single family home had fallen 13% since the market’s peak in April of last year. Meanwhile, in February, London saw its first annual decrease in prices in more than eight years, which accelerated in March and April. And in the first quarter of this year, Manhattan saw the median price-per-square foot fall 18% year-over-year.

No doubt, these declines can be attributed to region-specific supply and policy factors, whether newly-implemented government restrictions on foreign investment or Brexit and the U.S. tax reform bill. However, a recent report by the IMF sounds a troubling alarm: “a simultaneous decline in house prices across the globe could lead financial and macroeconomic instability.”

The IMF’s argument is intuitive. Accomodative monetary policy following the Global Financial Crisis drove an unprecedented flood of institutional and individual investor capital into real estate, with cross-border flows concentrating in cosmopolitan megacities. This has dramatically divorced megacity property-appreciation rates from economic fundamentals—primarily the spending power of residents. Moreover, it has made local housing markets far more intertwined with global economic conditions. According to the IMF, 30% of property price movements today can be attributed to global—not local—factors, up from just 10% two decades ago.

Now, with QE transitioning to QT, the IMF’s fear is that a reversal of financial conditions could cause cross-border capital to retreat from housing. Given the synchronicity between global megacities, instability could start anywhere and rapidly spread everywhere. The weakness seen today may not be a harbinger of a crisis anytime soon. However, as the lowest interest rates in history begin to normalize, a basic truth, articulated by Fed Chair Jay Powell last summer, requires increasing attention: “Housing is often found at the heart of financial crises”.

In Vancouver, home and condominium prices are up roughly 60% in just the past three years. In Sydney, house prices jumped over 80% between the end of 2009 and the peak last September. And in Toronto, Stockholm, Munich, London, and Hong Kong, housing rose by 50% on average since 2011. As the IMF writes: “In recent years, the simultaneous growth in house prices in many countries and cities located in advanced and emerging market economies parallels the coordinated run-up seen before the crisis.” The following chart illustrates both how widespread the megacity property boom has been, and the dramatic gap between city and nationwide appreciation in most countries:

Source: The International Monetary Fund

The escalation of cross-border institutional and individual investment in real estate has no doubt played an essential role in fueling megacity property booms. While data on foreign investment in cities is scarce and incomplete, the pattern is clear. According to the National Association of Realtors, U.S. home sales to foreigners surged 49% just between April 2016 and March 2017, reaching a record $153 billion. According to the Canadian government, foreigners now own at least 5% of Vancouver’s housing stock, a number that does not include Canadian immigrants who bought houses with funds from overseas. And according to a study released late last year by the Reserve Bank of Australia, foreign buyers accounted for roughly 25% of all property transactions in New South Wales and Victoria in 2015 and 2016, approximately three-and-a-half times greater than just five years earlier. 

The role being played by institutional investors is far easier to track. The IMF charts the escalation of their participation in global real-estate markets since the beginning of 2005:

Source: The International Monetary Fund

In its annual housing report released last September, UBS concluded: “The risk of a real estate bubble in top global cities has increased significantly in the past five years.” The role foreign and institutional money has played in escalating home prices beyond the spending power of the local population was at the heart of the Swiss bank’s concern....MORE