Barclays is to pay at least $450m after it was penalised for attempted manipulation of Libor, the interbank lending rate.
Barclays agreed to pay sums to the US Justice Department and the UK's Financial Services Authority, and will pay them fines of $160m and $92.8m respectively.
The US Commodity Futures Trading Commision handed out the penalty after it found that the bank had been falsely reporting the benchmark figure over a four year period, sometimes as often as once a day. It ordered the bank to pay $200m, and said it was the largest civil penalty it had ever imposed.
Libor is used to price over $350trn in financial products world wide. Barclays is not the only bank under investigation. Others include Citigroup, HSBC, RBS, and UBS.
Other authorities involved in investigating Barclays include the European Commission and Japan's Financial Services Authority.