Mosaic Co. said Monday that it has reached a deal to buy back 43.3 million restricted shares owned by trusts associated with the late Margaret Cargill, transactions valued at roughly $2 billion.

The share repurchase is related to the spinoff of Plymouth-based Mosaic from Cargill Inc., which was announced in early 2011. Wayzata-based Cargill, one of the world's largest private companies, was the majority owner of publicly traded Mosaic, a major global fertilizer producer.

The spinoff allowed for Cargill's stake in Mosaic to be distributed in a series of transactions, the largest involving the charitable trusts for ­Margaret Cargill, the granddaughter of Cargill's founder. Mosaic plans to buy back stock held by the trusts over the next eight months, with half of the purchases occurring in January.

Mosaic made clear earlier this year that it was interested in making significant repurchases of its own stock, including the stake held by the ­Margaret Cargill trusts.

Mosaic's purchase price for the Margaret Cargill trusts' shares will be based on the volume-weighted average closing price of Mosaic's stock ­during the 20-day period before the purchase. Mosaic's stock closed Monday at $46, down 79 cents or 1.7 percent.

Mike Hughlett