Allen & Overy and Shearman & Sterling completed their merger, the combined firm said Wednesday, with firm leadership boasting of a union that creates a $3.5 billion-grossing international law firm with nearly 4,000 lawyers, including 800 partners. 

Still, firm leadership said more steps are underway for the merged firm, A&O Shearman, including moving in together this year and beginning to work together on client matters. Meanwhile, the combined firm faces a long-term objective of reconciling cultures, observers say.