The SRB is believed to have sold 40,000 tonnes of copper on the Shanghai Futures Exchange, dealers said on Monday, with traders estimating it might sell around 100,000 tonnes of copper at home and abroad to rein in prices.
But London Metal Exchange (LME) stocks remain at historically low levels, with estimates that a stock at around 67,675 tonnes is enough only to meet global consumption for a day-and-a-half, supporting prices.
Three-month copper on the LME was trading at $3,974/$3,981 per tonne, roughly steady with $3,975 at the close in London on Monday. The metal had touched $3,992 earlier in the session, off a record high of $4,018 hit last month.
"It seems the market's ignoring the negative news for the price and quite happily absorbing the positive news,"Andrew Harrington, natural resources analyst at ANZ Bank, said.
Harrington said while the low stock figures are supportive, fundamental issues like an expected increase in supply is bearish for prices and sees prices over $4,000 as unsustainable.
LME stocks hit a 31-year low of around 25,000 tonnes in late July.
Shanghai copper futures dipped across the board, with the most active January contract shedding 100 yuan to trade at 36,690 yuan per tonne. Copper prices also defied a stronger US dollar, which usually sparks selling among base metals, with the currency hitting a two-year high against the euro and hovered near a two-year peak against the yen.
Aluminium was at $2,010/$2,015, down a touch from the London close of $2,023, and moving further from a new high of $2,040 hit last week, the highest level since February 1995.
Zinc was steady at $1,572/$1,579, hovering near a new eight-year high of $1,576. Lead was indicated at $973/$978, nickel $12,050/$12,150, while tin was at $6,350/$6,450.