Current shareholders would have a pre-emptive right to buy shares to stop their percentage share of the company diluting. New shares are usually valued at slightly below the current market price. It is generally up to the current board of directors to arrange a share issue, although there can be bylaws written into a company to limit the amount of share issues allowed (if any) A share issue may be underwritten, although this isn't necessary unless the company need an investment of a specific amount. They can get someone (usually a current major shareholder, but can be anyone else) to underwrite the share issue. Hope that helps.