U.S. grains merchant Bunge is merging with rival Viterra, which is backed by commodity trading titan Glencore.
Together they're worth $34 billion.
It will create one of the world's largest agriculture trading firms, with scale similar to rivals Cargill and Archer-Daniels-Midland.
That means it's likely to face scrutiny by competition watchdogs, with governments and officials around the world set to take note.
Bunge is already the world's largest processor of oilseeds.
It's also the biggest exporter of corn and soybeans from Brazil - the top source of the staple crops.
Combined, the two firms will account for almost a quarter of the country's overseas corn shipments.
It would also boost Bunge's presence in the U.S. - the world's number two corn and soy exporter.
Regulators may take an interest in big producer nations like Canada and Argentina too.
And it matters in Ukraine as well.
The war-torn country is the world's main source of sunflower oil, with the merged firm to be a big player in that market.
The deal is expected to close next year.
It's hoped the tie-up will quickly generate synergies of $250 million per year.
