It stands for well-known seasoned issuer; a category of issuers (of securities) that meet a set of requirements anytime within a 60-day period preceding the date an issuer fulfills its obligation to update its shelf registration statement (usually the date at which it files its Form 10-K or Form 20-F). Well-known seasoned issuers typically enjoy a host of flexibilities as to communications and registration.

For example, such issuers are allowed to register their securities offerings on shelf registration statements that, once filed, become automatically effective. Therefore, an issuer is not required to wait until the relevant authorities review and decide on effectiveness of its registration statement, before the issuer is officially allowed to embark on any securities sales.

A well-known seasoned issuer is by default an eligible issuer– that is, an issuer that has not been convicted of any felony or misdemeanor as specified by an exchange regulator (such as Stock and Exchange Commission– SEC). Other requirements include eligibility of an issuer to register a primary offering of its securities on Form S-3 or Form F-3. Furthermore, an issuer must have had an outstanding minimum amount ($700 million) in market value of voting and non-voting equity held by non-affiliates, any point in time within 60 days of its eligibility determination date. Eligibility may also be determined on the basis that an issuer has issued in the last three years non-convertible securities totaling at least $1 billion (other than common equity), in primary offerings for cash, not exchange.

Specific issuers, such as issuers of asset-backed-securities and registered investment companies, cannot get the status of well-known seasoned issuers.