Crystal Palace earned £18.8million more from selling Yannick Bolasie to Everton than the player's worth, according to an examination of the European transfer window, reports the London Evening Standard.

Everton agreed to part with around £29m to bring the 27-year-old winger to Goodison Park last month.

However, a study by the CIES Football Observatory, a research group founded in Switzerland in 2005, ranked Bolasie's true worth at just over £10m, making him the fourth most over-priced signings of a summer in which Premier League spending breached the billion pound mark.

Their figures claim that Palace sold assets worth just over £21m for a combined £47.2m. That certainly offsets the £7m for which the observatory believes they overpaid to bring in Christian Benteke from Liverpool.