This weekend The New York Times published a big story on Metro International Trade Services, a Detroit-based aluminum storage company owned by Goldman Sachs.

The NYT reported that Goldman shuffles the commodity around between storage units to skirt regulations meant to keep the commodity moving through the market and increase demand (and thus price) for the product. The paper calculated that this could have cost American consumers $5 billion over the last few years.

Goldman denies any wrongdoing.

And in fact, a source close to the situation told Business Insider that, as a rule, Goldman doesn't control the flow from its warehouses; the aluminum is owned by customers and they decide when it moves.

Then there's the aluminum that isn't governed by the London Mercantile Exchange, Metro's regulator.

"Roughly 95 percent of metal sold every year doesn't pass through the warehouse system, and Metro is just one company in the LME system," said the source.

Aluminum, like other commodities across the board, has seen its price drop dramatically since the financial crisis. Goldman points out that that is because of a lack of demand for the product.

Still, that isn't stopping banks from taking advantage of a 2003 regulation that allows them to jump into the commodities business. According to the NYT, JP Morgan and BlackRock are looking into purchasing 80% of the world's copper. Goldman has said it will not enter into that deal.