A 2.5 million pound ($4 million) loss contrasts with a 29.2 million pound profit that the Premier League club recorded in the corresponding period in 2009. Revenue also dropped from 196.8 million pounds to 120 million pounds.
While Arsenal made 33.9 million pounds from player sales in the 2009 offseason, primarily from the transfer of Kolo Toure and Emmanuel Adebayor to Manchester City, it only garnered an equivalent 4 million pounds in 2010.
The results were announced a day after Arsenal lost to Birmingham in the League Cup final at Wembley Stadium to leave the club still chasing its first trophy since 2005.
But the Gunners are still in the Champions League and the FA Cup, while sitting second in the Premier League they haven't won since 2004.
"Rather than seeing players leave, we have actually invested in the squad, so you expect to see a little bit of a change in the numbers. But we're still very healthy and robust looking forward," Arsenal chief executive Ivan Gazidis said on the club website.
"We've got a very young team, the average age against Barcelona (earlier this month) was just 23 years old. " Gazidis said the club is focusing on making sure it keeps key talents and signing them to long-term contracts.
A closer look at the figures shows that a slowdown in property sales on the site of Arsenal's former stadium in north London contributed to the loss.
A further 50 apartments at the Highbury Square development were sold in the six months to Nov. 30, generating 22.5 million pounds. In the same period in 2009, the sale of 261 apartments brought in 96.6 million pounds.
But with just 35 apartments yet to be sold, Arsenal is focusing on strengthening its commercial operations as it tries to emulate rival Manchester United, which has capitalized on its global brand to bring more cash into the club.
United, which is four points ahead of Arsenal in the Premier League, generated commercial revenues of 50.4 million pounds in the six months to Sept. 30. In contrast, Arsenal reported revenues of only 15.7 million in the six months to Nov. 30.
"Commercial is going to be a big focus for us, particularly globally," Gazidis said.
Arsenal's two largest shareholders are Stan Kroenke of the United States and Alisher Usmanov of Russia.
Kroenke, who owns the Denver Nuggets and Colorado Avalanche, has a 29.9 percent stake, while Usmanov owns 26 percent through his investment vehicle Red and White Holdings.