The Vienna Stock Exchange and a number of Austrian-owned banks have bought a 68.8% stake in Budapest Stock Exchange.
The Budapest Stock Exchange is now in majority Austrian ownership
Under the deal the Vienna Stock Exchange will own 14% of the Budapest bourse, while HVB Bank Hungary, a unit of Bank Austria will take 25.2%.
Three other Austrian banks share the remaining 29.6% of the deal.
The Vienna Stock Exchange said it was a "milestone" deal, but insisted that the Budapest Stock Exchange would retain its independence.
"We believe that both exchanges have a very high potential," said the head of the Vienna Stock Exchange, Stefan Zapotocky.
In a joint statement, the Austria investors said they were motivated by an "interest in the successful, durable and strong development of an independent Hungarian capital market."
The investment comes less than three weeks after Hungary joined the European Union.