Deposits decreased by £2.99 billion (-5.33%) to £53.09 billion between March 31st and June 30th, according to figures released by the Isle of Man Financial Supervision Commission.
And deposits in the year to June 30th decreased by £0.68 billion (-1.26%) on the corresponding figure from last year.
The FSC notes the figure to the end of June exclude the historic deposit base of Kaupthing Singer & Friedlander (Isle of Man) Limited following its liquidation.
KSF's deposit base was included in previous quarterly data.
The drop over the second quarter this year is being blamed on the pound's stronger performance against the euro and US dollar, meaning foreign currency deposits are worth less when measured in sterling.