The LME imposed a series of temporary rules on copper trading
on Tuesday October 19. The measures included a limit on tomorrow/next spread orders of higher than 0.5% of the previous day's cash price and a requirement for any party holding a position of more than 50% of LME warrants to lend at 0.25%.
After the rule changes, which came into effect immediately after the LME sent out a notice on Tuesday evening, the cash/three-month spread was trading at an implied $280 per tonne backwardation as of Thursday morning, easing from levels as high as $1,100 per tonne on Monday night.
The cash/November spread was at $200 per tonne on Thursday at around 9am, and the tomorrow/next spread was at a $4 per tonne backwardation at the same time, having flipped to a $1.90 per tonne contango on Wednesday at 12:30pm.