The two companies agreed to a deal in August in which Acer would acquire Gateway for $710m.
The purchase was expected to make Acer a major player in the consumer and enterprise PC markets, and provide an inroad to US retailers.
But some Gateway shareholders are unhappy with the terms of deal and have taken legal action.
Gateway disclosed in a series of filings with the SEC that two separate suits had been filed, both alleging that Acer and gateway were short-changing stockholders.
The first suit, filed on 31 August, alleges that each of Gateway's board members, the company itself, 25 unnamed individuals and Acer colluded to make a deal that "breached their fiduciary duties to stockholders".
The suit also referred to the purchase price as "inadequate and unfair" to investors.
A second suit was filed 10 days later targeting Gateway, its board and Acer. In addition to alleging an unfair price, the suit accuses Gateway of withholding information.
It also states that Gateway, with the aid of Acer, left stockholders in the dark about the proposed merger until it was too late.
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