Mittal Steel Co officially launched its US$27 billion offer for rival Arcelor SA, seeking a tie-up that would join the world's two largest steelmakers into a global titan.
The cash and stock offer launched in Luxembourg, France and Belgium is open until June 29. Mittal said it also will launch a bid in Spain and the US when market regulators clear the offer.
Arcelor, based in Luxembourg, has so far rejected the offer as hostile, saying the best thing for the company's shareholders is Arcelor's current management and plans.
In a move that could help Arcelor defend itself, the company has said it plans to spend up to US$9.5 billion to buy back almost a quarter of its shares.
Mittal chairman and CEO Lakshmi Mittal said in a statement that his company's offer has been well received by markets "through the considerable value created."
"We continue to believe that our offer is a very attractive one, structured to enable Arcelor shareholders to participate in the exciting growth potential of the combined company, whilst also receiving a generous cash element," he said.
The combined company would be the only steelmaker to stretch across the world, he said, offering a wide range of steel products and "ample captive" raw materials.
"We are confident shareholders will find great appeal in this model, whose strong growth profile will underpin superior shareholder returns," he said.
Arcelor chief executive Guy Dolle said last week when both companies reported earnings that Mittal's first-quarter figures were much weaker than Arcelor's.
"Our best defense is our results," he said.
Merging the world's top steelmakers would create a company with nearly a 10 percent share of global steel production and a market capitalization close to US$40 billion.