Sir Jim Ratcliffe's £1.5 billion ($1.9b) investment in Manchester United is unlikely to be finalised until after the January transfer window, sources told ESPN, even if the deal to buy 25% of the club is confirmed on the financial markets in the coming days.

Ratcliffe and his INEOS group have been engaged in detailed discussions since October with United's owners, the Glazer family, over the deal that will give the petrochemicals billionaire full control of football operations at the club.

- Stream on ESPN+: LaLiga, Bundesliga, more (U.S.)- What can we expect from Jim Ratcliffe at Man United?

Sources told ESPN that talks are in the final stages with recent delays because of legal details on both sides being reviewed before contracts are signed.

An announcement to the New York Stock Exchange could be made before the end of the year, although the holiday season might lead to a further holdup in this part of the process being completed.

But although Ratcliffe's team are already working on plans to overhaul United's football structure, sources have said that it will take between 4-6 weeks for the Premier League to ratify the change to the club's ownership model.

British businessman Sir Jim Ratcliffe has been in negotiations to purchase a 25% stake in Manchester United in recent weeks. VALERY HACHE/AFP via Getty Images

Due to the Christmas and New Year period, the ratification process might not begin until the first week of January, thereby leaving United facing the prospect of a final transfer window under Glazer ownership next month.

Colette Roche, United's chief operating officer, told a fan forum this week that financial restrictions will prevent the club from making significant additions to Erik ten Hag's squad next month.

Loan moves are possible, but with United needing to raise funds, no major incomings are likely, even if a deal is struck to offload Jadon Sancho, who has not been involved with the first team since a fallout with Ten Hag in September.