A fat-finger trade on the Shanghai Composite that was rumoured to have been executed by Everbright Securities triggered a wave of momentum buying and producer selling on the Shanghai Futures Exchange copper contract on Friday.

The Everbright trade moved the Shanghai Composite index 6% in two minutes and pushed several securities up towards their 10% intraday trading limit.

Shares in Everbright Securities itself jumped sharply before they were suspended, while China Everbright, its Hong Kong-listed subsidiary, was sold off heavily by short-sellers targeting the brokerage as rumours of the fat-finger trade spread.

The order unleashed a wave of momentum-driven buying in other asset classes on bourses across Asia.

In the copper market, investors helped to push the SHFE price higher in the Asian morning, while equally eager producer selling helped to put a cap on the rally, leaving the December contract up 1% at the close of trading.

The momentum also rippled over into the London Metal Exchange market, taking three-month copper to an intraday high of $7,420 per tonne, its highest level in two months, although most of the trading interest was centred on Shanghai and other Asian bourses.

The Shanghai Stock Exchange later said on Weibo that the rally was triggered by Everbright’s strategic investment department’s prop trading bureau as it traded with its in-house arbitrage system.