Troubles in emerging markets could stretch to the luxury apartment towers of New York and Miami.
Wealthy investors from Brazil and China have been big drivers of the high-end real-estate recovery—especially in New York, Miami and Los Angeles. But now, as emerging markets face slowing economies, sliding currencies and plunging stocks, the high-end real-estate market could feel the chill.
The biggest impact is likely to be Miami. Brazilians accounted for 12 percent of the city's real-estate sales in 2012, according to the Miami Association of Realtors. Yet they represent a far greater share at many of the high-end condo towers, which have helped lead the Miami real-estate recovery and building boom.
The majority of Brazilians buying in Florida purchased condos or apartments rather than detached family homes. And two-thirds of Brazilian buyers purchased homes priced at $200,000 or more, according to the association.
"The market could slow because of what's happening in Brazil," said Jorge Uribe, luxury real estate broker and senior vice president of One Sotheby's International in Miami. " I think there were a lot of people here putting a lot of emphasis on Brazil in terms of sales. And they could find themselves in a pickle."
Uribe said the troubles in Brazil could have both positive and negative effects on Miami. The luxury condo towers, with typical apartments selling for $500,000 to $3 million, could bear the brunt of the slowdown, he said. Such properties were purchased by upper-middle-class and single-digit millionaires, who have been hit harder by the stock market decline and economic turmoil.
Miami developments like Apogee, the Continuum and the MuranoGrande at Portofino all have large contingents of Brazilian buyers. At some condo towers downtown or in the so-called "Biscayne Corridor," 60 percent to 75 percent of the buyers have been Brazilian.
But Uribe said the very top of the region's luxury housing market could see a surge, as the ultra-rich in Latin America look for secure places to invest their still considerable fortunes. He said penthouses in a few select condo towers as well as waterfront mansions could see a rush of buyers looking for shelter from the economic storms.
"We may see an upside in the ultra-luxury market," Uribe said. "Whenever you have political turmoil in Columbia or Nicaragua or Latin America, you see an uptick in people buying assets here."
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In New York, the big focus is on Chinese buyers.
Brokers say the wealthy Chinese represent about 10 percent of the market. But some of the newer luxury towers are aimed squarely at rich Chinese buyers. One57, the residential skyscraper overlooking Central Park, has signed up several Chinese buyers. And 56 Leonard St, a downtown luxury tower, has also been popular with the Chinese.
Nikki Field, senior global real estate advisor with Sotheby's International Realty in New York, said Chinese buyers are still out in force. If anything, she said, the slowdown in China and turmoil in Asian markets could bring in more Chinese buyers into safer havens.
"They want to move a lot of money out as quickly as possible and get it somewhere safe," Field said. "Residential real estate here is safer than other options."
Still, other brokers say Chinese buyers have started dragging out their purchases over several months or even a year. And some newer developments are seeing delayed payments from Chinese buyers.
Field said Chinese buyers like newer apartment towers, and "many of them don't come on line for another two or three years." So if there is a slowdown, it may take another year or two to show up in the market.
"Of course, the last 48 hours brings us some concerns," Field said. Chinese stock markets have been volatile amid concerns about tighter credit, which would slow economic growth.
"But the people buying real estate here are not using their last $5 million. These are people who already have the extra funds offshore and are diversifying their portfolio."
—By CNBC's Robert Frank. Follow him on Twitter @robtfrank.