In separate statements, the companies said that although they had offered to make significant concessions, their offer apparently was not enough to satisfy competition concerns. 

"Based on the feedback received from the European Commission, it is increasingly clear that the commission is not intending to clear the proposed joint venture as it expects substantial remedies in the form of sale of assets of the proposed venture," Tata said in a statement. 

“From the point of the view of thyssenkrupp and Tata Steel, further commitments or improvements would adversely affect the intended synergies of the merger to such an extent that the economic logic of the joint venture would no longer be valid. Consequently, the partners assume that the European Commission will not approve the joint venture,” thyssenkrupp added.  

You can read the announcements from Tata and thyssenkrupp here and here. You can also read more coverage here and here.