Hong Kong's de facto central bank said Friday it found evidence that UBS attempted to rig a local benchmark interest rate, after a more than year-long investigation of nine banks concluded that the rate wasn't successfully manipulated.

The investigation into the Hong Kong interbank offered rate, or Hibor, by the Hong Kong Monetary Authority started in 2012 and reviewed millions of communications records after the authority received information from overseas regulators about alleged misconduct by UBS. It later widened the scope to include HSBC Holdings, Bank of Tokyo Mitsubishi, Citibank, Crédit Agricole, Deustche Bank, Royal Bank of Scotland and Societe Generale.