China's property sector, already a nagging economic risk, could become a victim of the unexpected weakening of the country's currency as developers face rising debt costs.
"Most Chinese developers are heavily exposed to U.S. dollar debt (up to 90 percent of their total debt) with no hedging," Credit Suisse said in a note Monday. "A potential renminbi depreciation may have a meaningful impact on both developers' earnings and net gearing – especially since Chinese developers are already highly levered financially."
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The fate of China's property sector is closely watched as a key economic risk. Capital Economics estimated that the property sector contributed 9.5 percent of China's gross domestic product (GDP) in 2013.
The renminbi, also known as the yuan, unexpectedly weakened recently, depreciating around 1.7 percent against the U.S. dollar since the beginning of February. The move caught many investors off guard as yuan appreciation was widely seen as a one-way bet. The currency has attracted considerable foreign investor demand over recent years on its steady appreciation and relative stability.
"China property stocks have long been considered a way to play the renminbi appreciation," Credit Suisse said, but it added, "the government hinted at a more balanced 'two-way trading' for renminbi going forward," which could dampen interest in the sector's stocks.
So far, the yuan's appreciation has flattered developers' earnings on the at least twice yearly revaluation of its foreign-currency debt as well as reducing gearing for many years, Credit Suisse noted. But the bank estimates that if the renminbi depreciates by 5-15 percent, some developers could see their reported earnings decline by as much as 74 percent while net gearing could increase by as much as 21 percentage point
For example, around 87 percent of China Overseas Land's debt is offshore, with nearly 33 percent of the total in U.S. dollars and around 55 percent in Hong Kong dollars, which are pegged to the U.S. dollar, the bank said, citing data from mid-2013.
It estimates COLI's net debt would increase by around 33 percent and its earnings would fall by 33 percent if the renminbi depreciates by 15 percent.
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Investors appear somewhat nervous about developers' U.S. dollar bonds. The weighted average yield of China property U.S. dollar bonds is currently around 8.77 percent, compared with 8.26 percent at the end of January, according to Deutsche Bank estimates.
The high-yield segment's yields rose to 10.04 percent from 9.31 percent at the end of January, the data show. Prices of bonds move inversely to yields.
The concern may not be limited to the property sector. Along with other emerging markets, China's offshore corporate debt has surged around 134 percent since the end of 2011, according to data from the Bank for International Settlements
To be sure, Credit Suisse notes that while the renminbi's weakness has increased the risks, the currency's move may only be temporary.
"The fundamentals do not support a reversed long-term trend for renminbi," it said. Many analysts have said they believe Beijing may have pushed the currency lower to shake out excessive speculation and that the yuan may resume appreciation later.
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Others also don't expect much of an impact on the property players.
"It really hasn't depreciated that much," said Sylvia Wong, a China property analyst at UOB KayHian. In addition, the net impact needs to be considered, she noted. "The renminbi has been going up. It's only coming back down."
She believes the impact will likely need to be measured on a company-by-company basis.
"Perhaps there's some paper profit and loss accounting impact, but the actual cash is really not that much, not yet anyway," she said.
—By CNBC.Com's Leslie Shaffer; Follow her on Twitter