De Ligt's move away from Ajax is set to be one of the biggest deals of the transfer window, with the 19-year-old having been linked to a number of Europe's biggest clubs.
Serie A champions Juve are the team who look set to secure the 19-year-old centre-back, however, for a reported fee of €66million.
Ajax confirmed on Sunday that De Ligt had been left out of their traveling squad for a pre-season trip to Austria, and Overmars believes the transfer is all but done, with the player expected in Turin to undergo a medical on Tuesday.
"The end of the transfer of De Ligt is near," Overmars told reporters.
"We're awaiting bank guarantees, because we are very strict with this at Ajax. Hopefully things will progress, but I think there will be no further obstructions. They are Italians."
De Ligt will leave a big void in Ajax's defense, with the youngster having been instrumental in leading Erik ten Hag's side to the Champions League semi-finals last term.
Mexico international Edson Alvarez could act as De Ligt's replacement, though Overmars insists the Club America centre-back would have been a target regardless.
"This transfer is not depending on the development of De Ligt's transfer," Overmars added.
"Edson is a player we think is good, so he might come to us. He is a good age, 21, and plays on a regular basis in the national team of Mexico and we know him very well because we scouted him over a longer period.
"He has progressed very well, and he can play in many positions."