. purchase of 20% ( 20 % ) equity interest in akbank in 2007 , citigroup completed its purchase of a 20% ( 20 % ) equity interest in akbank , the second-largest privately owned bank by assets in turkey for approximately $ 3.1 billion . this investment is accounted for using the equity method of accounting . sabanci holding , a 34% ( 34 % ) owner of akbank shares , and its subsidiaries have granted citigroup a right of first refusal or first offer over the sale of any of their akbank shares in the future