Why is Hong Kong the most expensive city for expats?

Hong Kong has the highest cost-of-living for expatriates, according to a new survey released Wednesday by Mercer, an international consulting firm, whose rankings take "currency fluctuations, cost inflation for goods and services, and instability of accommodation prices" into account to calculate how much employees will cost their corporations. 

The survey, which was conducted in March, uses New York City's own formidable cost of living as a point of comparison, according to a Mercer press release. All currency movements were measured against the US dollar. 

Luanda, Angola dropped to second place because of its weakening local currency. Currency fluctuations played a big role in this year's rankings, Mario Ferraro, one of the firm's global mobility leaders, told CNN. Zurich, Singapore, and Tokyo rounded out the top five. 

"The strengthening of the Japanese yen pushed Japanese cities up in the ranking. However, Chinese cities fell in the ranking due to the weakening of the Chinese yuan against the US dollar,” Nathalie Constantin-Métral, a Mercer principal who compiled the rankings, said in a press release. Shanghai came in seventh, while Beijing was tenth. 

In Hong Kong, however, the dollar "has remained fairly stable," Mr. Ferraro said. Combined with the city's high housing costs, that helped drive it into first place, as did the high price of imported goods and clothing. 

American cities do not break into the top ten. New York did move up five places, however, ranking 11th. Other major US cities also climbed in the poll, although less expensively: Portland (117) and Winston Salem, North Carolina (147), for example, are the survey's least expensive US cities for expatriates.

"Despite mild price increases overall, most cities in the US have climbed in the ranking, primarily due to a strong US dollar," said Ms. Constantin-Métral.

Although many of the most expensive expat cities are in Asia, the cost may not be such a hardship – for foreign employees, at least. Many expats in Asia reported having more disposable income than elsewhere, according to an HSBC survey in 2015. Their average salaries were $126,000, compared to the $104,000 expat average worldwide. 

But money isn't everything: HSBC's survey ranked Hong Kong's quality of life 21st, although Singapore was number five. Gold, silver, and bronze for quality of life went to New Zealand, Australia, and Sweden, respectively.