2008issue C051
Close imbalance prints as an exit filter
The scheduled close publishes leftover market-at-close size as a public residual tape. The first imbalance print shows whether an exit is racing unfilled demand or can wait, the republish shows whether that leftover survived offsetting flow, and the same residual reading decides whether an opening auction is executable.
- A long held into the last half-hour can be kept through a published buy imbalance or flattened immediately on a published sell imbalance, instead of being exited on clock time alone.
- End-of-session execution review follows a fixed checkpoint sequence: late-session inventory, the first imbalance print, the republish, the closing bell, and the final market-on-close price.
- After the republish, residual imbalance frequently shrinks by at least half, sometimes clears entirely, and sometimes reverses sign, so the first print is not the last word on leftover size.
- The same residual-size discipline that times a close exit is the opening-auction-strategy check that treats uncrossed demand as a reason to enter, exit, or stand aside.
A public leftover, not a clock
Market-on-close buys and sells accumulate through the session. They are not shown as a running continuous price. A market-at-close-order is a close-session instruction that is collected through the day and matched in the closing auction rather than at the contemporaneous continuous price.
What later becomes public is the leftover after paired orders are netted. An imbalance-print is the public leftover of unmatched close buys versus close sells after paired orders are netted. That leftover is the residual-size tape for the scheduled window.
How the first print is built
A first official print of one million buy shares against 500,000 sell shares is published as a 500,000-share residual so other participants can help complete the match. The published figure is the unmatched remainder, not the full book of close instructions.
Offsetting interest may be entered while the published imbalance remains visible. A republish is a later restatement of residual close size after offsetting orders have been entered against the first print. A 3:50 republish restates the residual after size entered between the 3:40 print and that republish.
The fixed close-session sequence
End-of-session execution review uses a fixed checkpoint sequence: late-session inventory, the first imbalance print, the republish, the closing bell, and the final market-on-close price. Each stop answers a different question about leftover size and fill.
After the republish, residual imbalance frequently shrinks by at least half, sometimes clears entirely, and sometimes reverses sign. The last print shown at the bell can keep updating for several minutes while market-on-close matching finishes, so the bell print is not always the official close.
Hold through a buy leftover, flatten a sell leftover
A long held into the last half-hour can be kept through a published buy imbalance or flattened immediately on a published sell imbalance, instead of being exited on clock time alone. The published side of the residual is the constraint on whether that exit is racing demand or can wait.
In a relatively flat tape a large buy imbalance is treated as more likely to coincide with upward pressure. After a sizable already-completed advance that association weakens and a fade of the first-print knee-jerk is considered.
Order-flow-analysis is reading published imbalance, offsetting interest, and related futures or derivative flow to judge implementation cost over the life of an order.
Futures, options, and the cash basket
When index futures trade above calculated fair value for that moment, large participants may sell the futures and buy the cash basket, adding immediate and longer-horizon upward pressure. The reverse applies when futures trade at a discount to fair value.
A fair-value-premium is index futures trading above the cash-implied fair value for that moment, a condition that can pull the underlying basket through paired futures and stock flow. Options and other derivatives add to cash-equity supply and demand, so observed price movement is not produced only by directional stock-order flow.
The same residual habit at the open
An opening-auction-strategy is the same residual-size discipline applied at the open: treat uncrossed demand as an execution constraint that decides whether an entry, exit, or abstention is timely. The open is another scheduled match with a public leftover, not a separate kind of tape.