Plug Power launched the secondary offering on Thursday after the close of market, when the company's last quoted price on the Nasdaq stock exchange was $7.09 per share, according to a prospectus filed with the federal Securities and Exchange Commission.

At that price, the public offering would raise nearly $78 million. The New York energy products company said in the SEC filing that after deducting underwriting costs, commissions and other expenses, the company would raise $73.4 million.

"We intend to use the net proceeds from this offering for working capital purposes, funds for operations, capital expenditures, research and product development, potential future acquisitions and general corporate purposes," the company said in the prospectus.

Citigroup is acting as the sole bookrunner for this offering and Little Rock-based Stephens will act as co-manager. Under an agreement with Plug Power, both brokerage firms will have a 30-day option to purchase up to 1.65 million additional shares of Plug Power's common stock to cover any over-allotments.

At Friday's close, the fuel cell maker ended at $7.15, down 35 cents or 4.67 percent. The company's shares peaked in the week ending session at $7.40 as nearly 950,000 shares traded hands.