PDI, one of the nation’s largest contract sales providers, said its stockholders will vote next month on the proposed sale of its commercial services business to Publicis Healthcare Communications Group.

Publicis had announced plans in early November to buy PDI’s commercial services business for $33 million, in addition to an earnout ranging between $5 million and $15 million depending on client commitments achieved during 2016.

The boards at Publicis and PDI have both approved the deal. The stockholder vote is scheduled for Dec. 22.

“We believe the addition of the PDI CSO business will enhance our position as a leading commercialization partner to pharmaceutical and biotech companies globally,” PHCG CEO Nicholas Colucci said in a Nov. 2 release.

PDI was founded as one of the nation’s first contract sales organizations. Now it also markets services like personal promotion, medical and clinical services and full product commercialization as well as developing and commercializing gastrointestinal and endocrinology diagnostic tests.

PDI’s commercial services compete with inVentiv Health, Quintiles and Publicis Touchpoint Solutions, which is part of Publicis Groupe. Its largest customers are Pfizer and Vivus, which made up nearly 70% of the company’s overall revenue in 2014, according to PDI’s 2014 annual report.

Revenue in the commercial services business fell 19% to $118.4 million in 2014, compared to $146.5 million in 2013. The commercial services business generated 98.7% of PDI’s total revenue in 2014.

If the deal goes through, it will be PDI’s second divestiture in the past year. In February PDI sold digital communications agency Group DCA to Haymarket Media. (Haymarket Media also publishes MM&M.)

“As part of our strategy, we have decided to sell our Group DCA business in an effort to reduce spending in the area and focus our resources on our strategic plan,” PDI said in its annual report.