Shares of Maxwell Technologies fell almost 12 percent on April 24, the day after the company announced it planned to sell $10 million in stock in a follow-on offering.

Maxwell (Nasdaq: MXWL) shares closed at $7.18 on April 23 and lost 11.8 percent to close at $6.33 the following day. Some 1.4 million shares traded hands, about two and a half times the three-month average reported by Yahoo Finance.

Maxwell produces heavy-duty capacitors for the transportation industry. One of its biggest customers is the Chinese bus industry, which is controlled by the Chinese government.

The company has agreed to let Cowen & Co. sell the $10 million in new shares at a 3 percent commission.