RAI will retain a majority stake, the broadcaster said in a statement, adding it would remain "open to assess further opportunities to develop Rai Way's business".
The state TV broadcaster currently owns a 65% stake in Rai Way, whose shares extended earlier losses after the statement to be down almost 7% by 1500 GMT.
Former Prime Minister Mario Draghi in March 2022 approved a decree allowing the stake to be cut to 30%, paving the way for the merger with EI Towers.
But Economy Minister Giancarlo Giorgetti, who served as industry minister under Draghi, said at the time he felt that RAI should not have control of the newly created entity.
Treasury sources told Reuters on Thursday that the stake sale would not prevent RAI from exploring the tie-up between Rai Way and EI Towers at a later stage.
RAI first floated the possibility of cutting its holding in December, drawing criticism from a group of minority investors in Rai Way including investment firms Amber Capital and Artemis, a letter sent to the state TV board and seen by Reuters showed.
The group of shareholders argued the stake disposal would extract less value for Rai Way's investors than a combination with EI Towers.
Under a previous blueprint for the discussed merger, Rai Way investors would have received an extraordinary dividend worth around 310 million-400 million euros, according to Kepler analyst calculations.
A separate source said an option being discussed currently would see RAI sell shares of Rai Way to one or more state-sponsored investors, in line with what Giorgetti advised last July.
The entry of new shareholders may therefore loosen RAI's grip on the combined entity.
EI Towers is 40%-owned by Italy's top commercial broadcaster MediaForEurope (MFE) controlled by the family of late media tycoon and political leader Silvio Berlusconi. Italian infrastructure fund F2i holds the remaining 60%.
($1 = 0.9185 euros)
(Editing by Gianluca Semeraro, Kirsten Donovan, Elaine Hardcastle)
By Giuseppe Fonte and Elvira Pollina
