It says this marks a third consecutive quarterly decline despite an ongoing current account deficit.
The agency says the third quarter decline mainly reflected the impact of stronger foreign equity markets, which pushed up the value of Canada's international assets more than that of international liabilities.
It says the gains were moderated by the downward revaluation effect of a stronger Canadian dollar on international assets and liabilities.
Canada's international assets rose $86.4 billion to $2.66 trillion by the end of the third quarter, with capital gains leading the increase.
The country's international liabilities increased $45.3 billion in the quarter, reflecting ongoing foreign investment in the Canadian corporate sector as well as an increase in Canadian stock prices.