Fiat Chrysler and PSA of France said Wednesday that they had agreed to the terms of a merger that would create the world’s fourth largest automaker.

The companies said they had signed a binding agreement formalizing the merger, announced in October.

The accord brings Fiat Chrysler and PSA, the maker of Peugeot and Citroën cars, much closer to creating a carmaker bigger than General Motors. But there will remain the task of integrating the companies. The companies said Wednesday that it would take another year to 15 months to close the deal.

John Elkann will become group chairman, while Carlos Tavares will be group CEO. Fiat Chrysler CEO Sergio Marchionne died last year.

The merger will be 50-50, according to the announcement, which added that no plants would be closed because of the transaction. The two companies have combined annual sales of 8.7 million units, with profits of €11 billion, or $12.2 billion.

Based on the two companies’ market caps, the new company will overtake Ford ($37.3 billion) in terms of value as well as give Peugeot presence in North America.

Peugeot stock rose 4.2% in morning trading in Europe, while FCA pushed up 1.7% also on the news of the merger.