It's been a roller-coaster of a week for Plug Power (PLUG 0.74%) shareholders. After delighting investors with a second-quarter earnings report that surpassed both top- and bottom-line expectations, it disappointed shareholders Tuesday -- shares plunged nearly 10% in after-hours trading -- with the prospect of dilution, announcing its intent to raise $300 million through a stock offering of about 31 million shares priced at $10.25 each. In addition, Plug Power said that it plans to offer the underwriter a 30-day option to purchase an additional $45 million in stock, representing about 4.6 million shares.

While investors may suspect that the company, which recently acquired United Hydrogen Group and Giner ELX, has its sights set on scooping up another company with the capital it will raise through the stock offering, Plug Power said it "has not designated any specific uses and has no current agreement with respect to any acquisition or strategic transaction." Instead, the company said it plans to use the proceeds "for working capital and other general corporate purposes."

People riding a roller coaster.

Image source: Getty Images.

For investors who had dug deep into the second-quarter earnings report, the company's decision to issue fresh stock probably wasn't a surprise since operating cash flow was negative $51 million in the period. Year to date, the company has used more than $111 million on cash from operations.

While it may be a necessary move to help the company to keep the lights on, investors are surely frustrated by the prospect of dilution -- something which they had already been experiencing due to Plug Power's difficulties in generating cash organically. Currently, Plug Power has about 366 million shares outstanding, 45% more than it had at this time last year.