Top 10 clubs that increased the overall value of their squad in the transfer market

8) Napoli: Increased by €228m

Can Marek and Insigne lead Napoli to become genuine title contenders?

Expenditure: €200m

Value: €428m

Napoli are another Italian club that have failed to capitalise on the potential of a good squad in recent years. There was a time when the trio of Edinson Cavani, Marek Hamsik and Ezequiel Lavezzi were lighting up Serie A before Gonzalo Higuain joined and set a few personal records. But those days are long gone and even then they never finished better than second. The club have not won a league title in 27 years and find themselves four points behind Juventus having played a game more this season.

After losing Cavani, Lavezzi and Higuain, club skipper Marek Hamsik is now their most valuable player at £34m – a £30m increase in market value since they signed the Slovak midfielder in 2007. Defender Kalidou Koulibaly (£25.5m) and winger Lorenzo Insigne (£21.3m) are the other two players who are valued at more than £20m.

Dries Mertens, the club’s top scorer this season, has also seen an increase in his transfer value and is now valued at £17m.