German-based pharmaceutical and crop chemicals company Bayer has reached an agreement to purchase American seed giant Monsanto for $66 billion. The new firm will control more than a quarter of the combined global seed and pesticide markets. 

Bayer is the second largest crop chemical company in the world, behind Syngenta, while Monsanto is a world leader in seeds and developer of the herbicide Roundup. Anti-trust experts predict the company will need to sell some seed assets, including soybeans, cotton and canola, before regulators will approve the deal.