Bayer said on Monday that the proposal made to Monsanto’s management represented a 37% premium over the closing price of Monsanto (MON) shares on May 9, before rumors of a planned bid emerged.

Monsanto disclosed last week that Bayer (BAYRY) had made an unsolicited takeover offer for the group, triggering an investor backlash in which one of the German company’s major shareholders called the move “arrogant empire-building.”

Bayer said it planned to finance the deal with a combination of debt and equity, primarily via a rights offering. Equity would account for about a quarter of the deal value.

It expects annual earnings contributions from synergies of around $1.5 billion after three years, plus additional future benefits from integrated offerings, a reference to Bayer’s push to combine the development and sale of seeds and crop protection chemicals.

“We have long respected Monsanto’s business and share their vision to create an integrated business that we believe is capable of generating substantial value for both companies’ shareholders,” Bayer Chief Executive Werner Baumann said in a statement.

Shares in Bayer were indicated 1.7% lower in pre-market trade, after slipping around 7% last week.

Bayer’s offer values Monsanto at 15.8 times its 12-month earnings before interest, tax, depreciation and amortization (EBITDA) as of Feb. 29.