Bayer Closes Monsanto Deal to Cap $63 Billion Transformation

Bayer AG closed its $63 billion acquisition of Monsanto Co., emerging from an arduous two-year antitrust review as the biggest seed and agricultural chemicals maker in the world.

The deal’s closing is just the beginning of another tough task: knitting the two companies together. Integration should begin in about two months, once the sale of some of Bayer’s agriculture assets to BASF SE is complete. The combined unit will be based in Monheim, Germany, while the North American business and seeds division will be led from St. Louis.

The transaction, which will double the size of Bayer’s agriculture business, means ...