Agricultural commodities company Archer Daniels Midland Co. (NYSE:ADM) announced Friday a A$3.4 billion ($3.5 billion) takeover pact with GrainCorp Ltd., unexpectedly returning to its target four months after failing to win the Sydney grains handler with a sweetened bid.

The so-called takeover bid implementation deed provides for GrainCorp to back a A$12.20 per share offer after Archer Daniels completes seven days of due diligence.

Although the headline per share price remains unchanged from December, Archer Daniels agreed that GrainCorp shareholders can receive a A$1 per share dividend before the transaction closes. If regulatory approvals aren't obtained by Oct. 1 -- a likely prospect given recent lengthy reviews by Chinese regulators -- the offer rises by A$0.35 per share for each full month of delay. At A$12.20 per share, the offer values GrainCorp's equity at about A$2.8 billion.

"We are pleased to have reached agreement with GrainCorp to conduct due diligence and, subject to that due diligence, put a recommended offer before GrainCorp's shareholders," Archer Daniels Midland chairman and CEO Patricia Woertz said. "We anticipate that the offer will be cash accretive in the first full year and will meet our key financial objectives."

In February Woertz said she hadn't held further takeover talks with GrainCorp after the target rejected the sweetened bid in December.

GrainCorp is the biggest grains handler on Australia's east coast, where it handles about 75% of all grains production and about 35% of Eastern Australia's grains exports.

Archer Daniels, of Decatur, Ill., has amassed a 19.8% GrainCorp stake, including a 14.9% holding it acquired before an initial October approach worth A$11.75 per share. The stake may have deterred potential rival suitors including Bunge Ltd., Cargill Inc. and Louis Dreyfus Holdings BV.

Including the dividend, the offer is 49% more than GrainCorp's undisturbed share price on Oct. 18, the target noted. The total A$3.4 billion price includes debt.

"The GrainCorp board believes that the ADM offer highlights the strategic value of our business and unique assets, the program of strategic initiatives being undertaken and GrainCorp's enviable proximity to the fast-growing Asian markets," GrainCorp chairman Don Taylor said in a statement.

The offer is contingent on Archer Daniels securing 50.1% of GrainCorp and on it obtaining regulatory clearances or waivers by Dec. 31.

Agricultural trading companies have been regular targets of dealmaking in recent months, with Glencore International plc in December closing its C$6 billion ($6 billion) takeover of Canada's Viterra Inc., while Japan's Marubeni Corp. in May agreed to pay $5.6 billion for the U.S.'s No. 3 grains handling company, Gavilon LLC.

Both transactions were delayed by regulators at China's Ministry of Commerce, which last week cleared Marubeni's deal with conditions.

GrainCorp shares rose 7.9% to A$12.81 in Sydney. Archer Daniels closed Thursday up 2.4% at $33.18, translating into a market value of $21.9 billion.

GrainCorp is taking advice from Credit Suisse Group's Max Billingham and John O'Sullivan and Greenhill & Co. LLC's Simon Mordant and Roger Feletto. It tapped Gilbert & Tobin's John Williamson-Noble and David Clee for legal counsel.

A Barclays plc team including Dan Janes, Anthony Lazzoppina, Julian Babich and Oliver Johnson and Citigroup Inc. are advising Archer Daniels. Corrs Chambers Westgarth's Braddon Jolley, Sandy Mak and Jeremy Horwood and Cravath, Swaine & Moore LLP's Richard Hall, Andrew R. Thompson, Stephen L. Gordon and Eric W. Hilfers are its legal advisers.

--David Marcus contributed to this report.