The Hammers have snapped up goalkeeper Darren Randolph and midfielder Pedro Obiang already this summer, and new manager Slaven Bilic will be keen to improve his squad even more ahead of the Europa League qualifiers.
However, they could face losing one of their key players, with winger Stewart Downing's future the subject of much discussion this week.
The 30-year-old hit six goals in 37 games for the Hammers last season, playing either as an attacking midfielder or out on the left hand side of midfield under Sam Allardyce.
Now, Sky Sports believe that Sunderland are looking to take the former Middlesbrough star back to the North East, with Dick Advocaat looking for reinforcements.
However, the Daily Mail report that West Ham are in no hurry to sell Downing this summer, suggesting if Sunderland really do want to sign Downing, they will have to make an offer that West Ham simply can't refuse.
Should West Ham sell Downing?
The ex-Liverpool flop enjoyed a decent season last term, and even earned a recall to the England squad in November 2014 as a reward for his fine performances.
Yet, at 30, West Ham should at least be thinking about a deal to sell Downing this summer, enabling them to cash in before his value plummets as he gets older.
New manager Bilic played a 4-2-3-1 system with pacey wingers at Besiktas, and selling Downing may help facilitate bringing new wide men to Upton Park this summer.
It's a risk considering his performances last season, but if the money is on the table from Sunderland, West Ham would be foolish not to at least consider a deal.