The Gunners unveiled the French international defender this morning after agreeing a £6.5million deal with Sevilla. He joins Marouane Chamakh and Laurent Koscielny as the only other new recruits.
Arsenal's pursuit of Fulham goalkeeper Mark Schwarzer has been well documented, with a £3m offer turned down earlier in the window. The Cottagers, though, are keen to hold on to the Australian stopper and Wenger appears to have given up hope of changing their mind.
Last man in: Arsene Wenger believes Sebastien Squillaci will be the last of the new arrivals this summer
'I'm not ruling it out but at the moment I'm not in a position to sign anyone,' Wenger said. 'At the moment, it is all dead.'
'No players will be going out domestically. Some could leave and go abroad, for example in Spain and Italy the season hasn't started yet. But once the season has started it is important that there is no movement.'
Experience: Squillaci has won titles in France and reached a Champions League final with Monaco
Wenger believes the extension of the transfer window the end of August disrupts teams during the season. It's a curious stance considering the Frenchman's penchant for deadline day deals, namely the arrival of William Gallas in 2006.
'I believe the transfer window should have been over already for a long time, he added. 'It should stop when the league starts for domestic transfers, internationally it can go on until August 31 because not everybody starts at the same time.'
While it seems the search for a goalkeeper will prove fruitless, the arrival of Squillaci does at least add more depth to a defensive unit shorn of four bodies.
The 30-year-old was part of the France's World Cup squad, was part of Monaco's Champions League final run in 2004 and also won back-to-back Ligue 1 titles in 2007 and 2008 with Lyon.
'This is an exciting move for me,' he said. 'Arsene Wenger is a highly respected coach who I am very much looking forward to working with and of course, I know some of the Arsenal players through the national team.
'Arsenal is recognised as a side that not only plays beautiful football but one that challenges for trophies at the highest level and I am very excited to be joining such a fantastic club.'
Wenger added: 'Sebastien has many qualities that will add to the strength of our squad. He is quick, hugely experienced with an aggressive edge to his game.
'His signing will give us some variation at the back as we look to build on last season's campaign and fight for silverware this year.'
Arsenal eye France keeper Landreau if bid for Fulham stopper Schwarzer failsArsenal boss Wenger accuses Potters of turning football into rugbyWenger wants Arsenal to put Euro new boys Spurs in their placeCHAMPIONS LEAGUE DRAW: Tottenham land holders Inter Milan while Manchester United and Rangers face Battle of BritainARSENAL FC