From Key Points About Regulation SHO:
II. “Naked” Short Sales
In a “naked” short sale, the seller does not borrow or arrange to borrow the securities in time to make delivery to the buyer within the standard three-day settlement period.[3] As a result, the seller fails to deliver securities to the buyer when delivery is due (known as a “failure to deliver” or “fail”).
Failures to deliver may result from either a short or a long sale. There may be legitimate reasons for a failure to deliver. For example, human or mechanical errors or processing delays can result from transferring securities in physical certificate rather than book-entry form, thus causing a failure to deliver on a long sale within the normal three-day settlement period. A fail may also result from “naked” short selling. For example, market makers who sell short thinly traded, illiquid stock in response to customer demand may encounter difficulty in obtaining securities when the time for delivery arrives.
“Naked” short selling is not necessarily a violation of the federal securities laws or the Commission’s rules. Indeed, in certain circumstances, “naked” short selling contributes to market liquidity. For example, broker-dealers that make a market in a security[4] generally stand ready to buy and sell the security on a regular and continuous basis at a publicly quoted price, even when there are no other buyers or sellers. Thus, market makers must sell a security to a buyer even when there are temporary shortages of that security available in the market. This may occur, for example, if there is a sudden surge in buying interest in that security, or if few investors are selling the security at that time. Because it may take a market maker considerable time to purchase or arrange to borrow the security, a market maker engaged in bona fide market making, particularly in a fast-moving market, may need to sell the security short without having arranged to borrow shares. This is especially true for market makers in thinly traded, illiquid stocks as there may be few shares available to purchase or borrow at a given time.
