This note covers U.S. SEC Rule 415, more widely known as shelf registration. It briefly discusses the rationale and historical origins of the rule in 1982 and then discusses several reforms?the introduction of universal registration statements in 1992 and well-known seasoned issuers in 2005?which have greatly expanded shelf-registered equity issuance. The more frequent use of shelf registration has led to the development of alternative methods of selling seasoned or follow-on equity offers, such as fully marketed offers, accelerated book building offers, and overnight offers.