Before the window even opened, United had committed funds to one of the most expensive arrivals in the club’s history, Brenden Aaronson.
Marsch was then reunited with more former players in Rasmus Kristensen and Tyler Adams as the American started the build a team for Premier League sucess.
Alongside Luis Sinisterra and Marc Roca, young prospects Sonny Perkins and Darko Gyabi were added to the roster - with potentially more players yet to arrive.
Thus far, the near-£100m spend has been covered by the big-money sales of Raphinha and Kalvin Phillips - but how does their net spend measure up to the other teams in the top flight?
Here we take a look at the expenditure-less-income of every Premier League team, ranked from biggest to smallest...
7. Manchester United, - £56.58m
With Paul Pogba and Jesse Lingard departing on free transfers, the Reds have only recouped £8.55m through the sale of Andreas Pereira. | Getty Images
8. Southampton, - £50.76m
The Saints have spent big on young players this window, while netting nothing for the departure of long-term St Mary’s resident Fraser Forster. | Getty Images
9. Crystal Palace, - £31.14m
Between Cheick Doucoure and Chris Richards, the Eagles have spent over £30m and are yet to recoup the costs through outgoings. | Getty Images
10. Brentford, - £28.71m
The Bees couldn’t hold onto their star player but have secured the services of rising young Championship star Keane Lewis-Potter for £17m. | Getty Images
11. Wolves, - £27.9m
The Midlands club have spent more than £30m on securing Burnley’s Nathan Collins and making Hwang Hee Chan’s loan switch permanent, but they could yet net a big fee for Morgan Gibbs-White. | Getty Images
12. Fulham, - £15.93m
In order to make this Premier League stint stick, the Craven Cottage outfit have bagged four permanent additions to their squad so far. | Getty Images