Molyneux acquired another 400,000 shares for $10,800, pushing his direct stake past 5 million.
This is his third purchase in January 2017, after snapping up shares as well in December 2016.
Molyneux is also the chief executive office of uranium producer Paladin Energy (ASX:PDN).
Argosy is focused on the Rincon joint venture lithium project which it intends to fast track to production of clean commercial grade lithium carbonate.
Rincon is located in the world’s most prolific lithium producing region of Argentina.