Both Bayer and Monsanto are launching asset sales worth roughly $2.5 billion as they seek regulatory clearance for a proposed $66 billion merger, sources recently told Reuters.

The two companies expressed, in the past, that they would likely need to divest activities with combined sales of up to $1.6 billion.

According to the sources, Bayer's advisers will commence the auction process by sending out informational packages this week to prospective bidders. The businesses have been divided into three bundles of assets, the sources said.

Monsanto shareholders approved the merger Dec. 13, 2016, and both companies anticipate that the deal will close by the end of 2017.