[PIPE is when] a private investment firm's, mutual fund's or other qualified investors' purchase of stock in a company at a discount to the current market value per share for the purpose of raising capital. There are two main types of PIPEs - traditional and structured. A traditional PIPE is one in which stock, either common or preferred, is issued at a set price to raise capital for the issuer. A structured PIPE, on the other hand, issues convertible debt (common or preferred shares).
This financing technique is popular due to the relative efficiency in time and cost of PIPEs, compared to more traditional forms of financing such as secondary offerings. In a PIPE offering there are less regulatory issues with the SEC and there is also no need for an expensive roadshow, lowering both the costs and time it takes to receive capital. PIPEs are great for small- to medium-sized public companies, which have a hard time accessing more traditional forms of equity financing.