3-D printing company ExOne (XONE) has announced that it will be issuing an additional 2.6 million shares of common stock. While this could raise around $179 million if sold at the current price, the move increases ExOne's share count by 20%, and the market didn't react positively to this dilution. In this video, Motley Fool industrials analyst Blake Bos tells investors why share dilution is a common risk when investing in very small growth companies, and gives investors the key metrics to watch in order to know whether the cash generated will fuel enough growth to make the stock dilution worthwhile.