Vestas, the world's largest wind turbine maker, said the complaint related to a change in its accounting policy last year and was without merit.
Vestas said the lawsuit was brought by a pension fund, which it declined to name, and it intended to defend itself vigorously.
In November 2010, Vestas adopted a new accounting policy that affected revenue recognition from a certain kind of contract and affected historic revenues up to the end of September 2010.
The change reduced equity by 739 million euros $1.05 billion and was heavily criticized by some analysts.
The company said the lawsuit filed in Federal district court in Colorado named Vestas and certain of its directors and officers as defendants. It did not identify the individuals.
"The company has reviewed the complaint with its legal and other advisors and believes that the complaint is without merit," Vestas Wind Systems A/S said. "The company and the individual defendants intend to defend themselves vigorously."
U.S. law firm Robbins Geller Rudman & Dowd LLP said in a statement that it brought a class action on behalf of an institutional investor in the U.S. District Court for the District of Colorado for purchasers of Vestas securities during the period between October 27, 2009 and October 25, 2010.
"The complaint charges Vestas and certain of its officers and directors with violations of the Securities Exchange Act of 1934," Robbins Geller Rudman & Dowd said.
"The complaint alleges that during the Class Period, defendants issued materially false and misleading statements regarding the Company's financial revenues and earnings, as well as its fiscal year 2010 financial guidance," the law firm said.
As a result, the law firm for the plaintiffs said, "Vestas' American Depository Receipts ADRs and ordinary shares traded at artificially inflated prices throughout the Class Period, reaching a high of $26.00 and $78.05 per share, respectively, on November 9, 2009."
"Plaintiff seeks to recover damages on behalf of all purchasers of Vestas securities during the Class Period," the law firm said.