The proposed $6.4bn acquisition of Affiliated Computer Services (ACS) by Xerox could be stalled as a result of class lawsuits filed by angry ACS shareholders.

Xerox announced that it was taking over ACS last month, as part of its strategy of expanding its document management services business. ACS provides lucrative data outsourcing services to both large government bodies and enterprises.

But the Shareholders Foundation is backing two lawsuits already filed in the US about the timing of the sale and the price ACS shareholders will get for the takeover.

ACS investors behind the two lawsuits are looking for other ACS shareholders to join them in class actions against the acquisition. The actions allege breaches of fiduciary duty and other violations of state law in connection with an alleged unfair takeover price. One lawsuit has been filed in Delaware and another in Texas.

ACS investors who purchased their shares before 28 September (the day the acquisition was announced) or have additional information relating to a Shareholders Foundation investigation, have been asked to contact the Foundation, with a view to joining the action to prevent the Xerox takeover.

The Foundation said, "One plaintiff alleges the process employed by ACS and its board of directors was unfair. The investor claims the agreement is unfair because, among other things, it allows ACS chairman Darwin Deason to continue to reap his $3.5m in compensation, plus benefits, until May of 2014."

The Foundation added, "According to the complaint, Deason agreed to vote all of his shares in favour of the takeover by Xerox. Deason's shares comprise a 43.6% ownership of the company. Additionally, the ACS Board agreed to a no-solicitation provision and a termination fee of $194m, which is designed to discourage any [other] potential bidders."

The Foundation also says the timing of the acquisition - amidst an economic downturn - may have undervalued the inherent value of ACS for shareholders.

ACS has so far not publicly responded to the lawsuits.