Chelsea have been the Premier League’s biggest earners in transfer markets since summer 2016 according to CIES Football Observatory.
The Blues have earned €660million or £579.6m) on transfers in the past five years, according to the Swiss-based research group.
It puts Chelsea in first place among Premier League clubs in terms of revenue from player sales.
This is significantly higher than Liverpool in second place with €474m (£416.6m) transfer income.

However, the report also claims that Chelsea have spent €968million (£850.6m) in the last five years, second-most in the Premier League (fourth in Europe).
Only Manchester City (just over €1bn or £883.9m) have spent more in England in the last five years.
It means Chelsea still spent €308m (£270.5m) more than they have earned which is the fifth-highest and ninth-highest figures in England and Europe, respectively.
Manchester City, Manchester United, Everton and, interestingly, Aston Villa all have had bigger negative net spending than Chelsea.
CIES also added that no Premier League club recorded a positive transfer balance during the period.

Chronicle view
Marina Granovskaia who is often viewed as a tough negotiator certainly played a big role in Chelsea’s success in transfer market revenue.
Diego Costa and Alvaro Morata’s reported £57m (The Times) and £58m (Goal) transfer fees paid by Atletico Madrid are just a few examples.
Not to mention that the two strikers clearly wanted to leave Stamford Bridge which put Chelsea in an unfavourable position in negotiations.
The transfer market revenue certainly has helped increase Chelsea’s spending power.
Chelsea have reportedly spent over £200m (BBC) in the last summer transfer window alone, although the 2019 transfer ban was also a big factor.
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