National Bank says it will write off the $165 million value of its investment in Toronto-based Maple Financial Group, which operates Maple Bank in Germany.

Maple Bank's business activities were suspended on the weekend by Germany's Financial Supervisory Authority, following investigations into certain trading activities during the 2006-2010 taxation years.

A spokeswoman for Maple Bank declined to comment, saying in an email that the bank is still "sorting out the whole complex situation."

Montreal-based National Bank owns 24.9 per cent of Maple Financial.

National said to its knowledge, none of its employees was involved in the trading and neither it nor its employees are subject to the investigations.

It says the writeoff of its Maple investment will be recorded in the first quarter of fiscal 2016.

Maple Financial Group is unrelated to Maple Acquisition Group, which bought the TMX in 2012.