For the whole of Europe, transfer spending was 29 percent up on last summer and 19 percent higher than the previous record 2017 summer.
The 80 clubs involved in the group stages of this year's Champions League and Europa League accounted for 58 percent of all money spent globally on transfer fees.
The 32 clubs in the Champions League and 48 in the Europa League spent a combined 3.98 billion euros ($4.39 billion), an increase of 55 percent from the summer window of 2018.
Forty-three percent of the clubs broke their record transfer signing.
The study does not include commissions paid to agents.
The 80 clubs, who also received 3.72 billion euros in fees paid, reported combined revenues of 11.7 billion euros and profits of 193 million euros in their most recent reporting.
Forwards and defenders were the most transferred players this summer, combining equally for 70 percent of all transfers, while clubs showed a marked preference for youth.
Players aged between 21 and 24 accounted for almost half of all summer transfers at 47 percent while only seven percent were of players aged over 28.