Nearly 171.1 million Flamingo shares changed hands at a price of 0.03 lei each, bourse data showed.
Flamingo shares were trading up 5.0% at 0.0315 lei by 1251 GMT on Monday.
The parties to the deal were not immediately known.
U.S. QVT Fund LP and individual investor Cinca Dragos Daniel were the largest single shareholders in Flamingo as of August 31 with respective stakes of 22% and 25.2%, bourse data showed.
(1 euro = 4.2798 Romanian lei)