The Dutchman has been linked with a move away from Bergamo after impressing with his performances during the 2023-24 season.
Koopmeiners registered 15 goals and seven assists in 51 competitive appearances, helping Atalanta win the Europa League, reach the Coppa Italia final and achieve a fourth-place finish.
The midfielder has been linked with a move to Liverpool, but the Reds are set to lose out to Italian giants Juventus.
According to journalist Fabrizio Romano, Juventus have reached an agreement with Atalanta to sign Koopmeiners in a deal worth €59m (£49.8m).
Juventus will pay an initial €52m (£43.9m) fee for Koopmeiners, plus a further €7m (£5.9m) in potential add-ons.
The Netherlands international has agreed a five-year deal and is set to undergo a medical on Wednesday before he is unveiled as the latest addition to Thiago Motta's side.
Atalanta set to sign Kossounou
While Koopmeiners is heading toward an Atalanta exit, Gian Piero Gasperini is set to strengthen his backline with the addition of Bayer Leverkusen defender Odilon Kossounou.
The 23-year-old played his part in Leverkusen's successful 2023-24 campaign, featuring in 34 competitive matches as die Werkself went on to win the Bundesliga title and the DFB-Pokal with an unbeaten domestic record.
However, Kossounou has been an unused substitute for the first two matches of the new season, with Xabi Alonso preferring to utilise Edmond Tapsoba, Piero Hincapie and Jonathan Tah.
According to journalist Fabrizio Romano, the Ivory Coast international is now on the verge of completing a move to Atalanta.
The Serie A side have reached an agreement with Leverkusen to sign Kossounou on an initial season-long loan deal.
Atalanta will pay a loan fee of €5.5m and will have the option to purchase the defender for €25m at the end of the season.
Kossounou's departure will pave the way for Leverkusen to complete the loan signing of Paris Saint-Germain defender Nordi Mukiele.
Roma agree deal to sign Danso
Staying in Italy, Roma have reached a verbal agreement with Lens to sign Austria international Kevin Danso.
Daniele De Rossi's side have made a number of additions this summer, having recruited Saud Abdulhamid, Samuel Dahl, Angelino, Matt Ryan, Matias Soule, Enzo Le Fee and Artem Dovbyk.
Roma are still keen to strengthen their squad before Friday's transfer deadline, and they are seemingly set to bolster their defensive options.
As per Fabrizio Romano, The Giallorossi have verbally agreed to sign Danso on a loan deal with an obligation to buy.
Roma will recruit Danso on an initial season-long loan move before signing him on a permanent transfer next summer for an initial €22m (£18.6m) fee plus €3m (£2.5m) in add-ons.
The Austria centre-back will leave Lens after making 117 competitive appearances during a three-year stay in France.