Manchester United have been known for forking out sumptuous amounts of money in certain instances. However, in recent years, the Red Devils have surpassed every other club, barring Manchester City, in terms of high-level spending. Once relying on their academy in search of future stars, Manchester United have amassed the second-highest net spend in the past five years among all European clubs. With so many expensive signings being sanctioned by United officials recently, the club has completely embraced the shift in their transfer policy.Manchester United and their expenditure latelyThe 20-time Premier League champions have spent more than €50m on a single transfer in all but one year since 2013. Romelu Lukaku, Angel Di Maria and current club captain Harry Maguire are some of the notable and most exorbitant signings made by Manchester United in recent years. However, the pick of the bunch has to be Paul Pogba's €105m homecoming from Juventus in 2016.NEW: Manchester United 'handed Declan Rice boost' as Chelsea eye alternative and more transfer rumours #mufc https://t.co/he4rJV2qjY— Man United News (@ManUtdMEN) September 7, 2021In the transfer window just gone by, Manchester United proved to be the second-biggest spenders in all of Europe, only behind their Premier League rivals Arsenal. Nevertheless, the Red Devils seem to have gotten their money's worth, acquiring Raphael Varane, Jadon Sancho and Cristiano Ronaldo for a combined fee of just €140m.With such extravagant expenditures on transfers, Manchester United have been able to attract some of the biggest names in modern football. However, they possess a tendency to hand bulky paychecks from time to time for not-so-worthy players. As a result, the English giants have one of the costliest wage bills in all of football. On that note, let's take a look at five of the most overpaid players that are currently registered on Manchester United's books:(Note: all wages are taken from spotrac.com)#5 Juan Mata - £160,000 per weekMata donates 1% of his salary to charityAt number five is Spanish veteran Juan Mata. The 33-year-old midfielder has been with the club since 2014, having recently signed an improved two-year contract in 2019 with an option to extend by one year. The aforementioned deal is set to expire towards the end of the ongoing season, which could free up £160k for Manchester United on a weekly basis.Proving to be a revelation at Chelsea, Mata joined the Red Devils for €44.73m and instantly won over the fans' approval. However, the World Cup winner has been reduced to a mere squad member in recent years. A victim of his own versatility, Mata has been deployed at various attacking positions to facilitate the team's functioning.Juan Mata’s annual wage costs more than Granada’s starting lineup...— Kaushik (@utd_kaushik) April 8, 2021As a result, the creative midfielder has seen his career stagnate on the bench. With no promised game time, Mata is set to endure another season on the sidelines, having made just nine Premier League appearances last season. Yet Manchester United continue to overpay him, without giving him a final call on his future.#4 Cristiano Ronaldo - £510,000 per weekRonaldo will don the number 7 jersey once againManchester United's least expensive but most significant signing this season, Cristiano Ronaldo's shock return to England made him the highest-paid player at Old Trafford. The Portuguese superstar had made his intention of leaving Juventus clear and was very close to joining Pep Guardiola's Manchester City.Jorge Mendes, the abiding agent of the Portugal international, concocted a generous agreement with Manchester United, which will see his client earn a massive £510k weekly salary. However, signing a 36-year-old player on such colossal wages for nostalgic reasons could put the English giants in deep trouble.What Cristiano Ronaldo’s annual salary at Man United can fund in Kenya pic.twitter.com/a1eZHyMadz— KTN Home (@ktnhome_) September 8, 2021Even though the Portuguese talisman flaunts the physique of a man in his mid-20s, he is still nearing the end of his illustrious career. Manchester United have him on a two-year deal, meaning that Ronaldo will be 38 at the end of his contract. During this period, United are liable to pay him a whopping £53 million in wages, not including all the performance-based variables that the two parties must've agreed upon.Cristiano Ronaldo has exuded immense commitment to the game and is easily one of the best footballers to have ever laced a pair of boots. While signing him could definitely be a worthwhile investment for Manchester United, giving him such towering wages might end up being a short-sighted move on the club's part. With the title of Premier League's highest-paid player on his head, Ronaldo will have to fire straight away to justify his monstrous salary.Also read: 5 players who could still leave the Premier League