Shares of Bunge fell 5% to $93.79 in premarket trading.
Viterra shareholders will receive about 65.6 million shares of Bunge stock, carrying a value of about $6.2 billion (€5.7 billion), and about $2.0 billion (€1.9 billion) in cash. Bunge will also assume $9.8 billion (€9.1 billion) of Viterra's debt.
Bunge is already the world's largest oilseed processor and analysts said it and Viterra's crushing businesses could face regulatory scrutiny in Canada and Argentina.
Bunge last year was the largest corn and soybean exporter from Brazil, the world's top source of the staple crops for making animal feed and biofuels, according to data from shipping agent Cargonave. Viterra was the third-largest corn exporter and No. 7 soybean shipper.
Combined, the companies accounted for about 23.7% of Brazil corn exports in 2022 and 20.9% of Brazil soybean exports, Cargonave data showed.
In the United States, Viterra's business of buying and selling grain expanded via its purchase of Gavilon last year. The merger would enhance Bunge's grain exporting and oilseed processing businesses in the world's No. 2 corn and soy exporter, where it has a smaller presence than ADM and Cargill.
The deal also expands Bunge's physical grain storage and handling capacity in major wheat exporter Australia, where the company currently operates just two grain elevators and a port terminal in the western part of the country. Viterra has 55 storage sites in South Australia and western Victoria and six bulk grain export terminals.
The world's top vegetable oils producer also entered partnerships with oil major Chevron and seeds and chemicals giant Bayer to pursue soaring demand for renewable fuels feedstocks.
In Ukraine, the world's top sunflower producer and largest supplier of sunflower oil, a combined Bunge-Viterra would have three oilseed processing plants across the country's south and east, in Kharkiv, Dnipro and Mykolaiv.
Acquiring Viterra would bring Bunge's revenue, which was $67.2 billion (€62.2 billion) in 2022, more in line with that of ADM, which registered sales of nearly $102 billion last year.
In early 2017, Viterra, then known as Glencore Agriculture, attempted a takeover of Bunge, which was then valued at $11 billion (€10.2 billion). The attempted takeover was rebuffed.