A total of £2.2m was spent on fees in the summer transfer window for Peterborough United, according to MacAnthony, who tweeted the statistics for the team.
But £1.4m was generated in sales, meaning the club's net spend was £800,000.
The co-chairman said nine new signings were made, plus three for the under 23s squad, and six players were sold, loaned or released.
The average age of the Posh squad is now 23.4 years old.
MacAnthony highlighted that the club had kept key players - and said it was "time to get to work".
T Window Numbers for @theposh— Darragh MacAnthony (@DMAC102) September 1, 2021
9 New Contracts signed
6 Players Sold, Loaned, Released
9 Signings bought,loaned,Free + 3 - Under 23 squad
Kept Key Players 😀
£2.2 million spent on Fee's
£1.4 mill generated in Sales
-£800K Net Spend
Average age Squad 23.4
Time to get to work :)
The transfer window deadline day saw two deals for Peterborough United, with Ethan Hamilton joining League One side Accrington Stanley and Conor Coventry loaned to Peterborough from West Ham.
Kobe Jae Chong arrived to strengthen the under 23s side on August 25 and Joel Randall and Kwame Poku signed for undisclosed fees at the beginning of the month.
Other signings for the main team in the transfer window include Oliver Norburn, Joe Tomlinson, Josh Knight, Jack Marriott, Jorge Grant and David Cornell.
As for big name departures: Mo Eisa left to join MK Dons, Flynn Clarke completed a move to Norwich City and Frazer Blake-Tracy was confirmed at Burton Albion.
Aaron Powell extended his contract for two years, Emmanuel Fernandez penned a two year contract at the club and Charlie O'Connell progressed through the academy to sign a two-year professional contract.
Midfielder Kyle Barker also signed a new contract, as did Mark Beevers.