A big summer awaits Barcelona after a disappointing end to their 2020-21 campaign.The club have already announced the signing of Sergio Aguero and Eric Garcia on free transfers, while Memphis Depay looks likely to join as well. Nevertheless, Barcelona need to trim their squad, considering their precarious financial situation. There is also the future of Lionel Messi and his impending contract extension the Blaugrana need to consider.On that note, let's take a look at five things Barcelona need to do in the transfer market this summer.#5 Sell fringe playersPhilippe Coutinho could be let go by Barcelona this summer.It is no secret that Barcelona's activity in recent transfer windows has left a lot to be desired. Ousmane Dembele, Antoine Griezmann and Philippe Coutinho are yet to fully justify their big-money moves to Camp Nou.Coutinho, in particular, has proved to be a catastrophic signing. There is no denying the Brazilian's talent. But Barcelona paid Liverpool an eye-watering fee of £121.5 million in January 2018 for Coutinho's services, but the player is yet to fit in at the club,Philippe Coutinho, Miralem Pjanic and Samuel Umtiti are among the players Barcelona could sell this summer, Goal can confirm 💰 pic.twitter.com/0VG6B2AyqL— Goal (@goal) June 8, 2021The 28-year old has made 90 appearances in all competitions for Barcelona, scoring 23 goals and providing 14 assists. Barcelona will suffer a huge loss if they decide to sell Coutinho this summer, but it is necessary to get the Brazilian's wages off their books.Similarly, striker Martin Braithwaite and left-back Junior Firpo, signed for a combined fee of £32.5 million, struggled for game time in 2020-21. Samuel Umtiti and Miralem Pjanic are two other big-names who could leave Barcelona this summer.Also Read: Strongest possible starting XI for England | UEFA Euro 2020.#4 Barcelona need to sign a midfielderSergio BusquetsIt was evident that Barcelona were after a midfielder when they offered a contract to Liverpool's Georginio Wijnaldum.The Netherlands international, whose Liverpool contract was about the expire, was very close to joining the Camp Nou outfit. However, Paris Saint-Germain came in with a better offer, and now it looks likely that Wijnaldum will join the Ligue 1 giants on a free transfer.Georginio Wijnaldum has just signed his contract with Paris Saint-Germain, confirmed and done deal. Medicals pending in the next hours then it’ll be official. Agreement until June 2024. 🇳🇱✍🏻Gini changed his mind yesterday - he’s not joining Barça and he’s now a new PSG player. https://t.co/HOs6YcGsPA— Fabrizio Romano (@FabrizioRomano) June 7, 2021While Frenkie de Jong is a nailed-on starter for Barcelona, the same cannot be said about the likes of Sergio Busquets and Miralem Pjanic. The 18-year old Pedri was one of Barcelona's best players last season, but at his age, consistent top-level performances cannot be expected.It is likely that Riqui Puig will get more chances next season, but Barcelona need to invest in a midfielder. With limited funds to work with, the La Liga giants will have to be shrewd about spending their money. Roma midfielders Lorenzo Pellegrini and Gonzalo Villar have been linked with Barcelona recently.Also Read: 5 stars Chelsea could sign this transfer window.