Was the investment in pound sterling?
The pound has been going down steadily over the last year.
And now we have a steep drop due to Brexit.
Am not speaking from a position of particular knowledge on this, but the
way I read original the email was simply that income was held in some kind
of depsit account in the currency in which it was received - so GBP income
remained in GBP until there was a need to spend GBP. WMF does after all
have significant expenditures in other currencies than dollars (e.g. grants
and salaries of overseas staff).
Regards,
Chris