DTC helps ensure the integrity of the FIFO queue by temporarily holding your position for transactions recycling due to risk management controls. This account is called the Pending Delivery Account (PDA). After your position is moved to the PDA, it is not available for other transactions that are recycling for insufficient position.
You can use the POSM function to move your PDA position back to your general free account to complete other items on the recycle queue. You can do this regardless of the deliveries that created the PDA position. For example:
Suppose a single delivery of 100 shares creates a 100-share PDA position in your account. The POSM function's PDA release feature allows you to move any quantity up to 100 shares from your PDA account back to your general free account. Assuming you release 75 shares from the PDA, when the 100-share delivery clears Risk Management Controls, the system looks for 100 shares in the PDA. With only 25 shares remaining in the PDA, the system looks for the additional 75 shares in your general free account to complete the 100-share delivery. If the shares are there, the delivery completes; if not, the delivery is placed at the end of your recycle queue, and the 25 shares in the PDA are released back to your general free account.
At the cutoff for syndicate closings (approximately 1:15 p.m. eastern time), DTC releases all PDA positions back to your general free account. At that time DTC also disables the "blockage" feature of option 2, allowing transactions for which there is sufficient position to complete while attempting to complete transactions you entered in FIFO order.
Warning! DTC cannot ensure FIFO ordering of transactions requiring RAD approval.