FuelCell Energy shares fell in after-hours trading Tuesday after the company announced the launch of a $200 million underwritten public offering of common stock.

Shares of the clean-energy technology company were recently down about 17% to $21.44.

The company said it expects to grant the underwriters a 30-day option to purchase up to an additional 15% of the shares offered.

FuelCell Energy said it plans to use the net proceeds for capital expenditures related to expanding its manufacturing capacity, as well as for working capital and general corporate purposes.

The offering is subject to market conditions, and the company said there can be no assurance regarding its timing, size or completion.

Citigroup and Barclays are serving as joint book-running managers for the offering.