FILE PHOTO: Monsanto logo is displayed on a screen where the stock is traded on the floor of the New York Stock Exchange (NYSE) in New York City, U.S. on May 9, 2016. REUTERS/Brendan McDermid/File Photo

WASHINGTON (Reuters) - German drug and crop chemical maker Bayer AG’s bid to buy seed and chemical company Monsanto Co is on track to win U.S. antitrust approval by the end of May, unless there is a last-minute complication, a source familiar with the matter said on Thursday.

The transaction, if it closes as seems likely, will create a company commanding more than a quarter of the combined world market for seeds and pesticides in the fast-consolidating farm supplies industry.