The following types of underwriting contracts are most common:
- In the firm commitment contract the underwriter guarantees the sale of the issued stock at the agreed-upon price. For the issuer, it is the safest but the most expensive type of the contracts, since the underwriter takes the risk of sale.
- In the best efforts contract the underwriter agrees to sell as many shares as possible at the agreed-upon price.
- Under the all-or-none contract the underwriter agrees either to sell the entire offering or to cancel the deal.
Stand-by underwriting, also known as strict underwriting or old-fashioned underwriting is a form of stock insurance: the issuer contracts the underwriter for the latter to purchase the shares the issuer failed to sell under stockholders' subscription and applications.