The Big Four banks are planning to put the final touch on their Gold Man scheme, a plan that promises to buy gold at cheap prices for a fraction of what they’re worth.

The scheme is set to go live in the first quarter of 2019, and is expected to provide banks with a cheap, secure way to buy up to $US7 billion ($US8.5 billion) worth of gold, a senior bank executive told the Financial Times.

In the scheme, banks will buy gold from brokers, who will sell the precious metal to banks at cheap and fair prices, and the banks will make money by selling the gold to other banks.

The plan has been criticised by critics, who have warned that banks could be making billions of dollars from the scheme.

Goldman Sachs said the plan was “unconventional and unproven”.

Goldman’s deputy chairman said the banks would be “investing in a new gold-buying platform” and that the banks’ own investment strategy was not affected by the plan.

“The strategy is the same as we’ve had since the end of the crisis: buy up gold from the banks at low prices,” said the executive.

While the banks are keen to avoid the pitfalls of gold speculation, there have been concerns that it could lead to a bubble in the market, particularly if investors start buying the metal in bulk.

Banks’ strategy has also been criticised because the money from the Gold Man will be pooled into a new fund that will be used to buy and sell gold to each of the banks.

Currently, banks must keep their own gold reserves in the bank and sell it at a profit to other investors.

Goldman said it would not put a dollar value on the Goldman scheme, but said it believed it was “a reasonable and prudent approach”.

“Our customers and clients will be able to access gold as they normally would, as long as we do our due diligence and maintain the confidence of our customers,” the bank said.

GoldMan has attracted criticism from gold traders, who argue that it is a way for banks to hedge against the risk of a gold price bubble.

Critics of the scheme have argued that it may not be as efficient as it is claimed to be, and that it would create a black hole in the financial system.