Manchester United has been facing challenges with contract clauses in the past, but they stand to gain significant financial benefits from the sale of Mason Greenwood to Marseille. The club sold Greenwood for £26.6 million in 2024, prioritizing long-term financial interests over immediate cash flow by including a hefty sell-on clause in the agreement. The reported sell-on clause entitles Manchester United to 50 percent of any future transfer fee received by Marseille; later reports suggest this might be adjusted to 40 percent.

Greenwood's status as a homegrown player means that the revenue from his transfer is considered pure profit under the Premier League's Profit and Sustainability Rules. This has crucial implications for the financial health of United, suggesting that should Greenwood be sold again for around £50 million, Manchester United could stand to earn either £25 million or £20 million depending on the accurate percentage of the sell-on clause. Furthermore, the structure of Greenwood's transfer not only aids in cushioning the club's finances but also highlights the strategic advantage of including such clauses in player contracts.

However, it’s important to note that Manchester United will not retain the entire sell-on amount, as a portion of the deal was previously agreed upon during Greenwood's loan period in 2023. This situation underscores the complexity and potential risks involved in contractual negotiations within professional football, while also turning a spotlight on the financial acumen required by clubs to navigate these transactions effectively. Overall, the case of Mason Greenwood illustrates the duality of contract clauses - both as potential pitfalls and as avenues for substantial revenue.