In securities lending, securities are classified by their availability to be borrowed. Highly liquid securities are considered "easy"; these products are easily found on the market should someone decide to borrow them for the purpose of selling them short. Securities that are illiquid in the market are classified as "hard". Due to various regulations, a short sale transaction in the United States and some other countries must be preceded by locating the security and quantity that one would like to be able to sell short in order to avoid naked shorting. However, the lending broker can create a list of securities that do not require such a locate. This list is referred to as an easy-to-borrow (abbreviated as ETB) list, and is also known as blanket assurances. Such a list is generated by broker-dealers based on "reasonable assurance"[1] that the securities on the list are readily available upon customer request. However, if a security on the list cannot be delivered as promised (a "failure to deliver" would occur), the assumption of reasonable grounds no longer applies. In order to provide better grounding for such assumptions, the ETB list must be at most 24 hours old.