Title-chasing Glentoran have brought in striker Andrew Mitchell and defender Caolan Marron from Glenavon with Calum Birney going the other way.
The clubs made a direct swap for Mitchell and Birney, while an undisclosed fee was agreed for Marron.
It's a major blow for Glenavon to lose two of their first team regulars after Rhys Marshall's recent departure to Shamrock Rovers.
Defender Birney joins the Lurgan Blues after eight years at the Oval.
Mitchell, 25, was the league's top goalscorer with Dungannon Swifts in 2016-17 before making the move to Glenavon.
The striker, who alongside Marron arrived n a two-and-a-half year deal, will add another option to Glentoran's already formidable frontline.
The east Belfast side are the league's second highest goalscorers with 51 goals, only Crusaders (58) have more.
While up front they have thrived, the Glens have at times struggled at the back and they will hope that Marron, 21, will help to solidify a defence that has shipped more goals than any other side in the top six.
The reigning Ulster Young Footballer of the Year made his debut for the Lurgan Blues in 2016.
News of two new arrivals comes shortly after Glentoran announced that Hrvoje Plum, Marijan Antolovic and Chris Gallagher had all penned contract extensions.
Under manager Mick McDermott the Glens have enjoyed an impressive season to date and find themselves second in the league table.
The campaign has been more of a struggle for Glenavon, whose hopes of claiming a top six spot have taken a sizeable hit in recent weeks following two draws and a defeat which sees them 10 points behind sixth-placed Larne.
In Birney they will be getting a player with considerable top-flight experience.
The defender, who joined the Glens from Linfield in 2011, was due to be out of contract at the Oval at the end of this season.