MGA acquired its stake through a number of individuals acting in concert with the company. Zapf's management board said it doesn't know the objective of the stake acquisition.
The purchase may affect the outcome of the $106 million bid made by Namco Bandai's German unit which aims to acquire 75 percent of the firm.
Zapf shares rose as much as 5.5 percent to €11.29 after the announcement.
A statement from Zapf is expected shortly.