It has paid for the dollars by printing more yuan, and has invested at least two-thirds of the dollars in American securities, particularly Treasury securities.
If considerably fewer dollars come in, China will not have the yuan to continue buying vast amounts of Treasuries, assuming it wants to keep buying them.
Over the weekend, China’s prime minister, Wen Jiabao, said, “Whether China will continue to buy, and how much to buy, should be in accordance with China’s needs, and depend on the safety and protection of value of foreign exchange.” The statement, reported by the semi-official China News Service, was taken by some analysts as official ambivalence.
Right now, the challenge for economists is figuring out why money is leaving China — and how long the trend will last.
Torrents of cash are still pouring in from trade surpluses, as imports shrank faster than exports in the final months of last year. But that inflow has been nearly balanced in recent months by an outflow of private cash from the mainland and a slowing of investment.
The quarterly pace of accumulation in China’s foreign exchange reserves plunged 74 percent over the course of last year. In the fourth quarter, it reached $40.45 billion, the lowest point since the spring of 2004.
Most economists say that actual capital flight seems the exception rather than the rule, and anecdotal evidence appears to bear that out.
Jewelry stores in Hong Kong are a barometer of trends on the mainland, because Hong Kong stores do not charge the luxury consumption taxes imposed on the mainland and have a reputation for not selling counterfeits.
Daniel Chun, the manager of Gaily Jewelry here, said he had seen an influx since December, with mainland Chinese mainly buying diamonds, either set in jewelry or as loose stones.
Sales to mainlanders were 50 percent higher at Chinese New Year this year compared to a year ago, he said, but cautioned that it was impossible to determine how much of the increase represented worries about China’s future.
Yet the Hong Kong government said on Monday that retail sales of jewelry, clocks and watches fell 9.8 percent in December.
While this may reflect plunging demand from local residents as Hong Kong’s economy slowed suddenly, it also indicates that demand from visitors, a big part of the market, could not have increased very quickly.
Hong Kong residents have been snapping up gold bars at a brisk pace in another sign of anxiety.
Few mainlanders have been willing to take the risk of flouting the mainland’s stringent gold import regulations, said Lin Tat Yin, a manager at Chow Tai Fook, a jewelry store chain.
Another motive for money coming out of China may be simply a perception, among individuals and companies, that better bargains are available elsewhere.
Soufun.com, an online real estate brokerage, is offering a tour for at least 40 people to San Francisco, Los Angeles, Las Vegas and New York City, starting on Feb. 24, and found that demand outstripped the spaces available.
“The people in the group are obviously interested in diversifying their investments, and the United States certainly is a very attractive location since real estate prices there have dropped drastically,” said Zhao Xingyu, a manager organizing the tour.
Chinese real estate industry executives say that there was considerable speculation here in recent years by overseas investors, especially overseas Chinese.
Those purchases contributed to a bubble that peaked last spring and has gradually deflated since, removing the incentive for further real estate investments here.
“Certainly a lot of the Hong Kong money seems to be coming back,” said Brad W. Setser, a fellow at the Council on Foreign Relations in New York.
Beijing’s slowing accumulations of Treasuries may be partly offset by Hong Kong’s increased purchases of Treasuries, he said.