Many copper participants questioned the normally secretive SRB's intentions and thought the bureau was trying to quell the red metal's momentous rise by jawboning it down.
"It certainly feels like that's what they're doing," said a New York dealer, pointing out that while other regions were selling copper on the SRB's announcement on Wednesday, traders in China were buying it.
"And that made a lot of people very skeptical," he said.
One trader pointed out the SRB's move to sell copper was a sign of how bullish the metal really is.
"Demand is so strong that these guys are going to release material. And, historically speaking, most interventions fail. I think people took it with a grain of salt," he said.
Another trader noted that when a market runs contrary to the news it is often a sign of underlying strength.
Inflation fears also buoyed copper, as funds bought in a search for tangible assets like metals after news that higher energy prices helped push the U.S. September trade deficit wider to record levels.
London Metal Exchange (LME) warehouse stocks fell by 1,100 tons to 65,350 tons on Friday. COMEX inventories remained unchanged at 3,690 short tons in Thursday's daily report.
LME three-months copper set an all-time high on Friday at $4,105 a ton, soaring far above the previous record set Thursday at $4,018, as it headed into the close.
