In January 2006, Arcelor's share was valued 2.9 times its 2005 EBITDA on the stock market. Six months later, Mittal's last offer to Arcelor amounted to 4.9 times its 2005 EBITDA. This paper studies the developments that took place between these two evaluations and their reasons. In the first part it will focus on the reasons for the merger, and in the second part on its details. To conclude, we will analyze if Mittal paid too much for Arcelor.