As background, the short stock availability list represents the inventory of shares which IBKR has available to lend and which other brokers have indicated that they have available to lend. While it is updated on a near real-time basis throughout the day for changes to IBKR's inventory and periodically throughout the day to reflect updates to the availability lists of other brokers, many brokers provide updates only once per day.

It should be noted that the purpose of the short stock availability list is to meet the broker's regulatory obligation that they have made a reasonable determination that a security can be borrowed in time for settlement three business days later. There is no regulatory requirement, in most instances, that the broker pre-borrow shares to effect delivery on a short sale prior to settlement and the requirement which this list serves to address is completely separate from the SEC rules which require that the broker force-close any short position having a delivery obligation subject to fail with the clearinghouse on any given day.

It is these rules which we are adhering to when we review your short positions relative to our settlement obligations with the clearinghouse each day. While the shares necessary to cover your short sale may have been available as of the date your trade took place and subsequently thereafter, there can be no assurance that those shares can be borrowed indefinitely. The inventory of available shares to borrow is dynamic and subject to change throughout a given day. When we believe that there is a reasonable chance that we will not be able to maintain your borrow position on a particular day, we will make every effort to provide you with a notice of those short positions which are likely to be bought in absent preemptive action on your part.