Critics have advocated for stricter regulations against naked short selling. In 2005 in the United States, "Regulation SHO" was enacted; requiring that broker-dealers have grounds to believe that shares will be available for a given stock transaction, and requiring that delivery take place within a limited time period. In 2008, the SEC banned what it called "abusive naked short selling" in the United States, as well as some other jurisdictions, as a method of driving down share prices. Failing to deliver shares is legal under certain circumstances, and naked short selling is not "per se" illegal. In the United States, naked short selling is covered by various SEC regulations which prohibit the practice.