SHANGHAI At Shanghai's Waigaoqiao port, a sprawling 10 square kilometer free-trade zone, thousands of tonnes of copper cathode plates sit in stacks turning green after years of exposure to the elements.
"They don't get shipped to end-users because they were bought for speculative reasons," said a warehouse manager at the port, who would only give his surname Zhu, standing in the port's control room overlooking yards piled high with metal.
The average time these copper stocks spend in bonded warehouses have stretched on to nearly one year from just two months in the past.
Some of this growing stockpile may never leave the port as fancy footwork from China's traders keeps them several steps ahead of official attempts to stop copper being used as proxy cash to punt on other markets.
After a regulatory clampdown on a wheeze to use copper as collateral for risky property investments, and a decline in property market prices, traders turned to exotic instruments such as offshore yuan forwards and interest rate differentials to squeeze a little extra profit out of their metal.
These increasingly savvy financing deals mean that what used to be reliable metrics of regional demand, such as draws from copper stockpiles in London Metal Exchange warehouses and copper imports to China, have become muddied.
They also mean the spread between the Hong Kong and Chinese yuan may be as important as China's industrial demand in determining imports.
"Today, a strategy purely based on trading LME stocks would still make money, but less money than, say, ten years ago. Financing deals have added another dimension to the fundamental picture," said metals strategist Michael Widmer of Bank of America-Merrill Lynch.
Some importers with years of experience are able to take advantage of different lending rates on offer.
"Traders have worked out some banks are smart at issuing LCs (Letters of Credit). Some issue them in yuan, some will issue them in U.S. dollars," said an analyst at a Western bank with China operations, who declined to be named because he is not authorized to talk about the bank's trading activities.
"You can take an LC from one bank, pledge it to another bank and borrow against it from another bank to take advantage of a whole range of different rates," he said.
"All we know is that we are selling a tremendous amount of metal to China for reasons that don't appear to be logical."
Previously, cash-strapped firms used metal imports to secure LCs, a much cheaper source of financing than official bank lending rates, in a simple swap to reap fatter rewards from other sectors.
They would sell the commodity or pledge the assets to another bank and use the money to invest in the red-hot real estate sector or to increase cash flow for their business. The shenanigan did not escape the regulators, who launched a series of crackdowns last year, such as forcing banks to lock part of the original collateral held against letters of credit in reserve accounts, taking the heat out of these vanilla cash-for-commodity plays.
"Property developers are not very active in financing anymore because the central bank has increased regulation. A lot of those doing the financing now are the trading firms, both international and local," said Judy Zhu, an analyst at Standard Chartered.
Given the slowdown in China's real estate sector and a toughening economic climate, some physical importers have morphed into currency speculators, looking to boost their profit margins by arbitraging between the onshore and offshore Chinese yuan markets. The offshore market, or CNH (Chinese yuan traded in Hong Kong), is largely the result of China's experiment to promote its currency's use in international trade and has traditionally traded at a higher value in dollar terms than the mainland yuan.
The premium for the offshore market has climbed as high as 3 percent over the onshore rate last year due to limited supply and high demand for exposure to the Chinese currency, whose trade is limited outside the mainland.
Before a selloff in the offshore markets in September, trading firms were using copper to fund a carry trade, where they secured LCs in low-yielding dollars to fund plays in the spread between onshore and offshore yuan, layering an element of FX gains on top of commodity price gains.
They could also speculate on the currency by using yuan non-deliverable forwards, which are contracts betting on the yuan's direction but settled in U.S. dollars.
"For a while, traders using this model were able to lock in profits almost immediately because of the difference in the onshore and offshore spread," said a copper trader at a foreign bank who requested anonymity because he was not allowed to talk about the bank's business. "The arb opened again in December so we should still see this sort of play in 2012, although the window will be less." The yuan rose 4.5 percent in 2011 and should appreciate by around 2.3 percent this year, according to a Reuters poll.
"These plays on currency spreads are simply a way of using money to grow money and the goal is to increase our cash flow," said a senior executive at a large Chinese metals trading firm.
Financing deals draw in surplus metal from as far away as New Orleans, greased by low freight rates and rent at Shanghai bonded warehouses that is a quarter of storage costs in other global ports monitored by the LME.
This has sucked the world's stock into China, tightening supply outside the country. As the global market moves into a small deficit this year, it has helped to firm premiums -- the price paid on top of LME contracts to get metal.
This means when the world economy picks up, an auto parts maker in Detroit, or a copper tube maker in Hamburg may have more trouble securing metal and may face higher costs to do so.
Financing has distorted buying patterns and prices, making successful price hedging even more of an obscure art. This has puzzled some traders who see only import costs and scant demand.
"It hasn't really changed the level of imports, but it has certainly changed the pattern of imports and the drivers around those imports," said the Western bank analyst.
It has also boosted demand for LME warrants, paper titles to specific bundles of metal, as financial instruments for Chinese companies.
Late last year, when the arbitrage between prices of copper on the LME and the Shanghai Futures Exchange (SHFE) encouraged imports, trading firms scrambled to get their hands on warrants and physical stocks, sending China's copper imports to a record high in December.
"That's the reason why there was a surge in cancelled warrants on the LME late last year. It wasn't downstream demand, but it was these trading houses looking to profit from the arb," said the copper trader with the foreign bank.
Imports are expected to moderate but remain high in March.
This has created an anomaly in which domestic buyers can draw stocks from Shanghai's free trade zone, before they turn to international markets. This has depressed Chinese prices compared to London prices for an unusually long time.
This means that the price differential or arbitrage between London and Shanghai copper - a flashpoint watched by funds - no longer gives a sound diagnosis of China's economic health or of its demand for the metal.
"The arb has spent more time being negative than you would normally expect for a country that is intrinsically short of copper to a degree of 3 million tonnes," the Western bank analyst added.
BIGGER, MORE DIVERSE
For now, the various plays on copper financing are only set to become more popular.
As part of Shanghai's ambitions to become an international financial centre, it is quadrupling floor space in bonded warehouses, where metal can be kept without clearing customs or paying import duties.
It has also lured a raft of firms, both local and foreign, to set up shop at the city's Yangshan Port, which is seeking a regulatory okay for bonded warehouse receipts to be used for financing, in much the same way as LME warrants.
Bonded copper stocks in Shanghai are expected to hit 600,000-650,000 tonnes by the end of March, about six times the expected deficit for the 20 million tonne market this year. Local traders estimate some 80-90 percent of the stocks belong to trading houses using imports as a way to get cheaper financing.
Lured by the prospect of growing their commodities trading business, as well as expanding trade finance services, at least six major Western banks have set up local units in China, alongside a stream of trading houses and two copper producers, with at least another three firms in the application process.
Industry sources said that until China normalizes its credit policies and , these financing deals are set to continue as banks grow their loan books and trading houses look for new ways to make money.
"At some point, China is going to normalize its monetary policy, at which point none of these financing trades will ever exist again," said the analyst at the Western bank.
(Additional reporting by Saikat Chatterjee in Hong Kong; Editing by Michael Urquhart)