Which housing market is the biggest real estate bubble? Depends on how you measure, and we won’t really know for sure until it pops. But according to the new UBS Global Real Estate Bubble Index, Hong Kong faces the greatest risk of a housing bubble.

Housing prices in the Hong Kong real estate market have increased by an annual rate of nearly 10 percent since 2012. Today, it would take 22 years of work before an individual would be able to afford a 650 square foot flat in the Hong Kong real estate market compared to the 12 years of work it would take just 10 years ago.

It’s not just Hong Kong. Affordability is a growing global housing crisis. Housing prices have increased by 35 percent in major cities over the last 5 years. Almost all cities introduced additional regulations ranging from levying stamp duties to rent-control measures as property became too pricey for citizens. Add in tighter lending conditions and a real estate boom can abruptly end, like it did for Sydney. Prices peaked there last summer and have since sloped as tighter lending conditions diminished overall affordability.

Homes in U.S. cities are well below their 2006 peak values, but real house prices in San Francisco have now exceeded their 2006 peak by more than 20 percent and are approaching bubble territory, according to the study.

Over the last six years real house prices in San Francisco have increased by 80 percent (12 percent in the last year – aren’t you sorry you didn’t hock everything to buy a home there a year ago) while inflation-adjusted incomes rose by only 20 percent meaning that affordability has worsened dramatically in both the local homeownership and rental markets.

Chicago is the only city in the study that was determined to be undervalued. Inflation-adjusted prices remain almost 30 percent below their 2006 peak. Other than weather, there are a number of issues that are challenging real estate values in the Windy City. The report cites issues like lackluster economic growth, sluggish employment and a challenging fiscal outlook that, “hinder a faster recovery of broad-based housing demand.” UBS expects price growth in Chicago to continue to lag the national average.

(Which, if you think about it, is a positive for companies looking for a headquarters where their workers can actually afford to live close to the office.)

Although many global and U.S. cities remain at risk of a housing bubble, the report found no evidence of simultaneous excesses in lending and construction that were seen in the years preceding the 2008 market crash. If you’re worried, real estate investors should stay away from cities that are seriously overvalued if they expect real price appreciation in the medium to long run.