* FT reports Danske executed mirror trades for Russian clients
* Shares slide 8 percent
* Credit Suisse downgrades Danske
COPENHAGEN, Oct 5 (Reuters) - Shares in Danske Bank plummeted on Friday to their lowest level in four years after a media report the bank executed up to 8.5 billion euros of mirror trades for Russian customers in 2013 and a downgrade by Credit Suisse.
An internal memo seen by Financial Times indicates that Danske Bank executed mirror trades in 2013 of between 6 billion euros and 8.5 billion euros, the UK newspaper reported on Friday.
Danske shares were trading 9.8 percent lower at 0744 GMT. (Reporting by Jacob Gronholt-Pedersen; Editing by Jan Harvey)