A ransomware attack on the financial services arm of China’s largest bank has disrupted the US Treasury market by forcing clients of the Industrial and Commercial Bank of China to reroute trades, market participants said on Thursday.

The Securities Industry and Financial Markets Association first told members on Wednesday that ICBC Financial Services had been hit by ransomware software, which paralyses computer systems unless a payment is made, several people familiar with the discussions said.

The attack prevented ICBC FS from settling Treasury trades on behalf of other market participants, according to traders and banks, with some equity trades also affected. Market participants including hedge funds and asset managers rerouted trades because of the disruption and the attack had some effect on Treasury market liquidity, according to trading sources, but it was not impairing the market’s overall functioning.