Arsenal reportedly stand to receive around £2m from the transfer of former academy graduate Mark McGuinness from Cardiff City to Luton Town.
The 23-year-old spent a decade in the Gunners' academy ranks from 2011 to 2021, but he never made a competitive first-team appearance for Arsenal, nor did he make it into a single senior matchday squad.
Following a productive loan spell with Ipswich Town in the 2020-21 season, McGuinness left Arsenal permanently for Cardiff, who paid exactly £2m to prise him away from North London.
McGuinness became a stalwart of the Bluebirds' defence, in addition to spending the first half of the 2022-23 season on loan at Sheffield Wednesday, and he scored in his first appearance of the 2024-25 season against Bristol Rovers in the EFL Cup.
That would prove to be the 23-year-old's last act in the Cardiff shirt, as he has now been unveiled as a new Luton player after the Hatters agreed a £10m fee with their Championship counterparts.
According to the Evening Standard, Arsenal agreed a sell-on clause with Cardiff when they sold McGuinness in 2021, which entitled them to 30% of any profit that the Bluebirds made on a future sale.
As a result, Arsenal's coffers will be boosted by around £2m through the centre-back's move to Luton, where he will link up with Reuell Walters, another Hale End academy graduate who left the Gunners this summer.
That windfall follows a reported £4m that Arsenal made from Omari Hutchinson's transfer from Chelsea to Ipswich Town earlier this summer, and they will also be entitled to a cut of any future move for Danish striker Mika Biereth, who joined Sturm Graz for £4m several weeks ago.
"I'm excited to be here. It's been nice to see the boys today and get a feel of the camp," McGuinness told LTFC+. "Cardiff was a great platform for me to go and develop, and get to that next stage and that next level – and for me, Luton Town was the perfect next stage."
How much money have Arsenal made this summer?
Including Hutchinson and McGuinness's windfalls, Arsenal have now banked around £38.7m this summer, where Emile Smith Rowe - a £27m move to Fulham - has been their only big-money departure so far.
Biereth (£4m) is one of two Under-21s players to seek pastures new, as right-back Brooke Norton-Cuffy has left for Serie A side Genoa in a deal worth an initial £1.7m, although it could reach £3.5m with add-ons.
Eddie Nketiah is also believed to be close to joining Nottingham Forest in a £30m deal, while Reiss Nelson, Aaron Ramsdale, Kieran Tierney and Jakub Kiwior have good chances to depart before the window closes.
Arsenal have traditionally struggled to sell players for their market value, but should Nketiah and the aforementioned quartet also head for the exit door, they could easily make over £100m through player sales this summer.
Mohamed Elneny, Cedric Soares and Arthur Okonkwo leaving on free transfers have also trimmed Arsenal's wage bill, as have the loan exits of Nuno Tavares (Lazio), Karl Hein (Real Valladolid) and Albert Sambi Lokonga (Sevilla).