Granit Xhaka has become Arsenal's third most expensive signing after joining from Borussia Monchengladbach.
While the transfer fee has been undisclosed, Sky Sports News HQ understands Arsenal are paying in the region of £30m for midfielder Xhaka.
After calls to "spend, spend, spend" over recent seasons, Arsenal look to be treating their supporters to an early summer gift in the form of the 23-year-old.
A fee of around £30m would be almost double that paid for the current third-highest signing in the club's history; the £17m, including add-ons, for Jose Antonio Reyes from Sevilla in 2004.
The £41.5m handed to Real Madrid for Mesut Ozil still tops the spending list for Arsenal, with Alexis Sanchez, £35m from Barcelona, in 2014 second.
Compared to other clubs, Arsenal's signings over £20m have been few and far between. Manchester City have signed 20 players for £20m or more, while Manchester United have signed 13, Chelsea 15 and Liverpool nine.
Arsenal's highest transfer fees
|Mesut Ozil||Real Madrid||£42.5m|
|Granit Xhaka||Borussia Monchengladbach||£30m|
|Jose Antonio Reyes||Sevilla||£17.4m|
|Danny Welbeck||Manchester United||£16m|
Andrey Arshavin (£16.95m from Zenit), Calum Chambers (£16m from Southampton), Danny Welbeck (£16m from Manchester United) are Arsenal's next highest signings, surpassing the £13m paid to Bordeaux for Sylvain Wiltord in 2000 and Alex Oxlade-Chamberlain (£12m from Southampton) in 2011.
There have been varying reports on the amount of money Arsenal have to spend this summer, but Wenger warned fans in April that the recruitment process is as not as easy as it sounds.
"We have to strengthen our squad but it's not obvious to find the players despite the money the English clubs will have," said Wenger.
"Of course, we will work very hard to do that. We are already working. But we have to find the players and that is not easy."
Arsenal were top of the Premier League at Christmas, but ended up stumbling in late winter and early spring before a late revival saw them finish second.
They have failed to pass the round of 16 in the Champions League for the past six seasons, with some fans becoming impatient at Wenger's tactics in the transfer market.