AIM - Automated Improvement Mechanism

Cboe's Automated Improvement Mechanism (AIM) is an automated process for crossing of any origin type, which provides potential for price improvement and a participation right through an auction process. By utilizing the AIM crossing mechanism, an order flow provider is afforded the opportunity to participate against their customers' orders (facilitation) or solicit another firm's liquidity (solicitation).

(NOTE: During Regular Trading Hours (RTH) AIM is available in all classes except SPX, SPXW, OEX and XEO. There must be at least 3 Market Makers quoting the relevant series to begin an AIM auction. AIM All or None (AON) Solicitation (SAM) is available in all Cboe non-exclusive classes. During Extended Trading Hours (ETH) AIM is available in all classes).

See the table below for AIM rules for :

  • AIM for Simple (non-complex) Orders
  • AIM Customer to Customer Transactions
  • AIM for Complex Orders
  • AIM All Or None (AON) Solicitation (SAM)- Simple and Complex

AIM for Simple (non-complex) Orders

Initiating Order and Contra Order must be entered as a pair.
Contra Order must be for full size of Initiating Order / can be facilitating or solicited.
Price must better NBBO if 49 contracts or less; 50 contracts or above can equal NBBO.
Auction period is 100ms; minimum improvement increment is .01. Contra Order guaranteed 40% if at best price (matched by multiple participants) or 50% (matched by one participant).
Entering Contra Order as a Market Order guarantees participation at best price (auto-matches best price of other auction participants).

AIM Cust-to-Cust (Simple and Complex)

If both orders are Customer origin execution is immediate - no exposure to auction.
Cannot trade at same price as resting Customer order(s).
The Contra Order must be submitted with a limit price in a standard increment for the class (i.e., .01, .05 or .10). Contra Orders not sent in standard increments or marked "MKT" will be exposed to the standard AIM auction.
All else, same rules as above.

AIM Auto-Match and Auto-Match With A Limit

Allows the contra order submitted by the order provider to join the price and quantity of other auction responses. A limit price can be included to allow the contra/match order to join other responses, but only up to a stated limit price. Note that in both of these cases, the price on the contra/match order is "market". Thus, the system will automatically determine the auction starting price, based on a combination of the NBBO, best available prices within the Exchange's electronic book, and the quantity and price on the AIM primary/agency order.

Starting Price on Contra/Match Order

With AIM Auto-Match the auction starting price may be designated by including a limit in the price field and market in the contingency price field of the contra/match order. The contra/match order will join the price and quantity of other auction responses. With AIM Auto-Match with a limit the auction starting price may be established by sending a limit in the price field and a limit price in the contingency price of the contra/match order. The contra/match order will join the price and quantity of other responses up to the limit contained in the contingency price field.

AIM For Complex Orders*

Complex orders having up to four legs and having a ratio of one-to-three or higher or three-to-one or lower are eligible for the AIM mechanism.
Contra Order price must be at least .01 better than Cboe displayed market.
All else, same as AIM for Simple Orders.

AIM All Or None (AON) Solicitation (SAM) - Simple and Complex

500 contract minimum.
Both orders must be AON.
Solicitation only (no Facilitated). If Contra Order is Firm, cannot be same give-up as Initiating Order.
Price must be at or within NBBO for Simple Orders. Complex Orders must be within Cboe BBO by at least $.01.
Contra Order can only be shut out if responses improve Contra Order price FOR FULL VOLUME.
All else same as AIM for Simple Orders.