There aren't a lot of certainties when it comes to buying players in the transfer market, everybody has risks and nobody can be entirely sure if a purchase (or sale) can work out favorably or blow up in a club's face. There seems to be one exception to this rule however: if you want to win a league title (but definitely not the Champions League) then buy Zlatan Ibrahimovic. In the past 10 years he has failed to be on top of the table only once (in the 11/12 season with Milan).
With both of the clubs from Milan aiming to fight at the top portion of the table next season, additions are necessary and for some, the thought of bringing Ibra back does not sound like the worst idea in the world (especially since his age means a transfer fee would not be all that large). With AC Milan doing some serious bolstering of their attack so far there were numerous reports and statements that they are trying to bring the Swedish striker back to the club that he spent time at at after a disappointing spell at Barcelona.
But of course newspapers love a story, and what's bigger than Milan going after Ibra? Inter going after Ibra as well. After how big the stealing of Kondogbia from right under the nose of Milan was, the media figured it would be a massive headline that there was another Milan derby in the transfer market. Never mind that Inter already have a star striker in Icardi (who finished joint top of the Serie A scoring charts). Never mind that the team has enough experienced leaders on the team. Never mind that the wage structure has already been thrown off with the new additions and Ibra would probably want something around €7m a year (which would absolutely throw the wage balance deep into the red).
So how did Inter respond to these rumors? They shut them down because they used common sense.
How did Milan respond to these rumors? They threw more money at Ibra because apparently throwing money at somebody always solves your problems, even if those problems are just transfer rumors that have no basis whatsoever.
It's surprising that clubs are influenced by reports that come out in the papers, even when the team could find out if there is any truth to the story by a simple phone call, going and meeting when representatives from the other team (because they're kind of in the same city...) or simply using common sense to realize that Inter would not waste their time going after Ibra. But hey, when you have money to blow, who needs common sense?