New York--Ending months of speculation on Wall Street that it would succumb to the sour economy and reduce its headcount, Citigroup announced it will fire 7,800 employees, or 4% of its work force. The cuts come half a year after Citigroup, the world's largest bank and a b-to-b e-commerce leader, bought Banamex, a big Mexico City-based corporate banking company, for $12.5 billion, and nine months after it bought New York-based European American Bank for $1.6 billion. Citigroup will bear the brunt of the cuts, with 4,200 jobs being eliminated. Banamex will lose 3,600 positions. Citigroup did not reveal where the job cuts would come, though it is speculated that many would come from its investment banking department.