Self Match Prevention (SMP)

Self Match Prevention (SMP) functionality in Starbase API for preventing orders from matching with each other.

Overview

Self Match Prevention (SMP) is a mechanism that prevents orders from matching with each other when they originate from the same member AND share the same SMP token. SMP helps prevent accidental self-trading and allows for more granular control over order matching behavior.

SMP uses three components to control order matching:

Component	Description	Required	Scope
SMP Mode	Determines which order is cancelled when a self-match is detected	Per order (default configured in Thunder account settings or via private/set_self_trading_config)	Order-level
SMP Token	Prevents matching between orders with the same token	Mandatory (can be set to null/0)	Order-level
Member ID	Scopes SMP to a specific member	SMP cannot trigger between Members	Member-level

SMP Mode

SMP mode determines which order is cancelled when a self-match is detected:

Mode	Behavior
CANCEL_MAKER	The resting (maker) order is cancelled
CANCEL_TAKER	The incoming (taker) order is cancelled

The SMP mode should be specified for each order. A default SMP mode can be configured in Thunder through account settings or via the private/set_self_trading_config method, and users can change their default setting.

SMP Mode Selection: When a self-match is detected, the SMP mode from the aggressing order (the incoming order) will be used to determine which order is cancelled.

SMP Token

The SMP token is a mandatory field in order messages that prevents matching between orders with the same token within the same Member. The field must always be present, but can be set to null (0) to allow self-matching.

Matching Scenarios

Matching is prevented only when both of the following conditions are met:

• The same member ID (or both orders lack a member ID)
• The same SMP token (non-null)

Scenario	Member	SMP Token	Matching Behavior
Same member, same token	Same	Same (non-null)	Prevented
Same member, different tokens	Same	Different	Allowed
Same member, null token	Same	Null	Allowed (self-matching allowed)
Different members	Different	Same (non-null)	Allowed
Different members	Different	Different	Allowed

Key Points:

• SMP token is a mandatory field that must be specified on each order
• Setting SMP token to null (0) allows self-matching
• Orders with the same SMP token (non-null) within the same Member will not match
• Two orders with the same SMP token from different Members can match

Member

Self-match prevention is scoped to a Member (a group of portfolios representing a trading participant). Two orders with the same SMP token within the same Member cannot match, but two orders with the same SMP token from different Members can match.

Order from different systems

Orders originating from the Websocket API, User Interface or other non-Starbase origin will have the SMP Token set based on the table below. To avoid matching with these orders when utilizing Starbase APIs, the same SMP Tokens should be used.

Setting	SMP Token Value
Self-match prevention restricted to subaccount	sub-account id (equal to Deribit’s User ID)
Self-match prevention enabled across all subaccounts	main-account id (equal to Deribit’s User ID)
Self-matching allowed	null (empty)

API Usage

Order Entry Messages

SMP fields are mandatory and must be specified in the following order entry messages:

Message	SMP Token Field	Field Number	Description
NewOrderRequest	SMPToken	7	This order cannot match with any other orders within the same portfolio with the same token. Set to null to allow self-matching.
MassQuoteRequest	SMPToken	4	This order cannot match with any other orders within the same portfolio with the same token. Set to null to allow self-matching.

SMP Cancellation Indicators

When an order is cancelled due to self-match prevention, it will be indicated in the response messages:

Message	Field	Value	Description
NewOrderResponse	cancelReason (field 11)	1	selfMatchPrevention
AmendOrderResponse	cancelReason (field 12)	1	selfMatchPrevention
MassQuoteResponse	buyQuoteStatus (field 18)	7	CanceledBySelfMatch
MassQuoteResponse	sellQuoteStatus (field 19)	7	CanceledBySelfMatch