American Superconductor ( AMSC) fired David Paratore, its president and chief operating officer, after a female employee made sexual harassment allegations.

The company said it would search for a replacement. CEO Greg Yurek will take over Paratore's duties in the meantime. The termination takes effect June 28 under the terms of Paratore's employment contract, American Superconductor said.

The news comes on the heels of a wild run-up in shares of the Westborough, Mass., power converter company. Shares of American Superconductor surged 24% in regular trading Monday after Needham & Co. upgraded the stock, reasoning that a recent selloff wasn't warranted by developments at the company.

After rising $1.82 to $9.45 in regular action, the stock dropped 3 cents in postclose trading.