"The words Volkswagen and the German language sadly no longer go together," Walter Krämer of the German Language Foundation said in a statement.
"I am dismayed at how thoughtless our elites are giving up their own language and culture," he added.
Volkswagen last week announced it was switching the group's business language from German to English, saying the change would help it recruit the best and brightest in the industry.
According to the Handelsblatt financial daily, the German Language Foundation bought 200 Volkswagen shares at €100 a piece last year, and sold them on Wednesday for €137 each - netting a tidy profit of €7,400.
A global auto giant, Volkswagen was founded in 1937 in the northern German city of Wolfsburg and still has its headquarters there.
Adolf Hitler himself laid the foundation stone for the first Volkswagen factory, tasked with building an affordable car for all Germans - which would go on to become the iconic Beetle.