BST (Bank-Securities Transfer) Overview

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What: Full comparison of integration models, protocol differences, limit systems, and exception handling across the three BST banks Audience: Product managers who need a deep understanding of BST channel details Prerequisites: Withdrawal Methods Overview, Bank Capability MatrixReading time: 6 minutes Owner: Deposit Product Manager

Key Takeaway: BST (Bank-Securities Transfer) is the fastest withdrawal channel. The three banks have vastly different protocols: CMB/CMBC use Socket bidirectional links (second-level response), while Airstar uses REST API polling (minute-level response).

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Three Banks at a Glance

Dimension	CMB	CMBC	Airstar
Protocol	Socket Binary (GB18030)	Socket XML Text (SM2 Encryption)	REST API (JSON/UTF-8)
Authorization Model	BST Agreement	BST Agreement	Mandate Authorization (6 states)
Withdrawal Initiator	Both bank-side + moomoo-side	Bank-side only	Both moomoo-side + bank-side
Result Delivery	Real-time push (Socket callback)	Real-time push (Socket callback)	Polling
Deposit Status	Success / Failure	Success / Failure	NEW / PENDING / SUCCESS / FAILED / REFUNDED
Withdrawal Status	0 (Success) / -5 (Timeout) / -6 (Rejected)	0 (Success) / -5 (Timeout) / -6 (Rejected)	NEW / PENDING / SUCCESS / FAILED

Core difference in one sentence: CMB and CMBC use traditional Socket dedicated lines (bank-led), while Airstar uses a modern REST API (moomoo-led).

Individual Bank Channel Interface Details

This page provides a high-level comparison of BST protocols. For channel-side interface fields, moomoo-side adaptation mappings, and complete matching rules for each bank, see the individual bank pages:

• CMB — Socket binary protocol, 33 command codes, SM2 encryption
• CMBC (MS) — XML text protocol, SM2 encryption, Socket communication
• Airstar — REST API, RSA-OAEP encryption, 10 API methods

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BST Authorization (Mandate)

Authorization Model Comparison

	CMB / CMBC	Airstar
Terminology	BST Agreement	Mandate Authorization
Initiation Method	User completes agreement on bank side	User initiates on moomoo side, confirmed by bank
Number of States	2 (Signed / Unsigned)	6 (Full state machine)
Multi-market	Separate agreement per market	One authorization auto-maps to 3 markets
Core Identifier	Bank card number	mandate_id

Airstar Mandate State Machine

Automatic 3-Market Mapping: After a user completes one Airstar Mandate authorization, the system automatically creates BST binding relationships for HK (Hong Kong stocks), US (US stocks), and CN (A-share connect) markets. Users do not need to operate separately for each market.

mandate_id is Airstar's core identifier: Unlike CMB/CMBC which use bank card numbers as the primary key, Airstar uses mandate_id as the unique identifier for BST relationships. All operations for bank card management, deposits, and withdrawals are linked through mandate_id.

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Deposit Flow Comparison

Common BST Deposit

All BST banks share the same deposit logic framework:

1. User initiates deposit -> System creates deposit instruction -> Sends to bank -> Bank processes -> Result returned -> Funds credited

Airstar Deposit Specifics

Two deposit sources:

Source	source Value	Description
User initiates on moomoo side	1	User clicks deposit in moomoo App
User initiates on bank side	2	User initiates transfer to securities account in Airstar Bank App

Bank-side initiation (source=2) is unique to Airstar — CMB/CMBC BST deposits can only be initiated from the moomoo side.

Polling mechanism:

Unlike CMB/CMBC which push results in real-time via Socket, moomoo actively polls Airstar:

Job Name	Responsibility	Poll Count	Description
AsbBstCreateJob	Create deposit instruction	—	Sends deposit request to Airstar
AsbBstCreateResultJob	Poll deposit result	Up to 60 + slow polling	Polls Airstar API at intervals to check deposit status
AsbBstDepositJob	Process deposit credit	—	Executes internal credit logic after deposit confirmed successful

First 60 polls at 5-second intervals; after 60, switches to slow polling every 5 minutes until a terminal state is reached or manual intervention.

REFUNDED Status (Airstar-exclusive):

Airstar deposits have a status that other BST banks lack — REFUNDED. This indicates that after funds were successfully credited, the bank initiated a refund.

Trigger scenarios:

• Bank detects transaction anomaly and proactively refunds
• Compliance reasons trigger refund

System handling: Upon receiving REFUNDED status, the system must reverse the already-credited funds and notify the user. This is an exception scenario requiring Operations attention.

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Withdrawal Flow Comparison

Common BST Withdrawal

BST withdrawal follows the Freeze-Transfer-Release three-step pattern:

Why freeze first? Because there is a time window between sending the instruction and bank confirmation. Without freezing, the user could spend the money during this period, causing a negative balance. Freezing ensures the withdrawal amount cannot be used by other operations during processing.

Airstar Withdrawal Specifics

Two withdrawal modes:

Mode	Description
moomoo-side initiated	User clicks withdrawal in moomoo App, system sends instruction via API
Bank-side initiated	User initiates transfer from securities account to bank in Airstar Bank App (Airstar exclusive)

Polling mechanism:

Job Name	Responsibility	Retries	Description
AsbBstTransfer	Withdrawal transfer instruction	Up to 10	Sends withdrawal request and polls result
SyncAsbBstWithdraw	Bank-side withdrawal pull	Every minute cron	Pulls bank-side initiated withdrawal requests, creates moomoo-side withdrawal tasks

Flow: moomoo-side withdrawal -> AsbBstTransfer polls up to 10 times -> if still incomplete, marks as exception needing manual confirmation. Bank-side withdrawal -> SyncAsbBstWithdraw pulls every minute -> creates withdrawal task for processing.

CMB / CMBC Withdrawal

CMB and CMBC send withdrawal instructions via Socket connection:

1. Withdrawal service calls BST service (cmb_stock_trans / ms_stock_bank_transaction)
2. Encrypts request data
3. Sends to bank's exit_server via Socket
4. Bank processes and returns result in real-time via the same bidirectional link
5. Result codes: 0 (Success) / -5 (Timeout, auto-switch to backup exit_server for retry) / -6 (Bank rejected)

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Three-Tier Limit System

BST channels control per-transaction amount, cumulative amount, and daily amount in layers. See Withdrawal Rules Manual - Three-Tier Limits for detailed explanation.

Airstar Limit Details

Dimension	HKD	USD
Per-transaction max	3,000,000	500,000
Cumulative alarm	40,000,000	10,000,000
Daily circuit breaker (stop)	15,000,000	3,000,000

Online account opening minimum deposit: HKD 10,000 / USD 1,500 / CNH 10,000

How the three tiers work together:

• Tier 1 (Per-transaction): Single deposits/withdrawals exceeding HKD 3M are directly rejected
• Tier 2 (Cumulative alarm): When cumulative reaches HKD 40M, an alert notifies Operations, but transactions continue
• Tier 3 (Daily circuit breaker): When daily cumulative reaches HKD 15M, auto deposit/withdrawal is shut down for the day; subsequent transactions require manual processing

CMB / CMBC Limits

CMB/CMBC Limit Explanation

CMB and CMBC limits are controlled by the bank-side system (not moomoo configuration). Specific values need to be confirmed with the bank. They are known to have per-transaction and daily limit mechanisms; when exceeded, the bank directly rejects and returns callback code -6. For over-limit issues, refer to Withdrawal Troubleshooting - BST Callback Exceptions.

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Online Account Opening (Airstar Exclusive)

Airstar supports a three-in-one online account opening flow — new customers can complete in one continuous process:

1. Open securities account: Complete KYC identity verification
2. Mandate authorization: Authorize Airstar Bank for BST
3. First deposit: Complete first deposit to securities account

The value of this flow is new customer acquisition — it lowers the barrier from registration to tradeable status. The traditional process requires users to switch between multiple systems (open account -> go to bank for agreement -> come back to deposit); the three-in-one flow is completed end-to-end within the moomoo App.

Online account opening deposit restrictions: The first deposit has a minimum amount requirement (HKD 10,000 / USD 1,500 / CNH 10,000), higher than regular deposit minimums, to ensure new customers have sufficient funds for trading.

Airstar Only

CMB and CMBC BST agreements must be completed on the bank side, and do not support the three-in-one flow within moomoo.

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Cron Jobs

Airstar Job List

Job Name	Responsibility	Frequency	Retries	Dependency
AsbBstCreateJob	Create BST deposit instruction	Trigger-based	—	User deposit request
AsbBstCreateResultJob	Poll deposit result	Scheduled	Slow poll after 60	AsbBstCreateJob
AsbBstDepositJob	Deposit credit processing	Trigger-based	—	AsbBstCreateResultJob returns SUCCESS
AsbBstTransfer	Withdrawal transfer + poll result	Trigger-based	Up to 10	Approval passed
SyncAsbBstWithdraw	Bank-side withdrawal pull	Every minute cron	—	Bank-side initiated withdrawal
AsbBstCreateFromBankJob	Bank-side deposit processing	Trigger-based	—	Bank-side initiated deposit
AsbBstCreateRetryJob	Deposit creation retry	Trigger-based	—	AsbBstCreateJob failure

Job Chain:

Deposit: AsbBstCreateJob (moomoo-side) / AsbBstCreateFromBankJob (bank-side) -> AsbBstCreateResultJob (60 fast polls + slow poll) -> AsbBstDepositJob (credit)

Withdrawal: moomoo-side: AsbBstTransfer (poll 10 times) -> timeout needs manual confirmation | Bank-side: SyncAsbBstWithdraw (pull every minute) -> creates withdrawal task

CMB / CMBC Jobs

Service Name	Bank	Responsibility
cmb_stock_trans	CMB	BST service, Socket binary communication
ms_stock_bank_transaction	CMBC	BST service, Socket XML text communication

CMB/CMBC use real-time bidirectional Socket, requiring no polling jobs — the bank pushes results directly through the same connection after processing.

Full cron job list -> Cron Jobs & Monitoring

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Exception Scenarios Manual

Authorization Exceptions (5 types)

#	Exception	Symptom	Cause	Resolution
1	Authorization timeout	Mandate stuck in PendingAuthorise state	Bank processing delay or communication interruption	Wait + manually query bank-side status
2	Authorization failure	Mandate becomes RejectAuthorise	User info verification failed / bank-side risk control	Investigate failure cause, guide user to re-initiate
3	Authorization revocation	Mandate becomes Revoked	User initiated revocation	Confirm user intent, re-authorize if needed
4	Partial market authorization failure	Some of 3 markets binding succeeded	BST configuration issue for certain market	Check failed market config, manually supplement binding
5	Bank-side revocation not synced	Bank-side already revoked but moomoo still shows Authorised	Sync delay or callback lost	Manually sync Mandate status

Deposit Exceptions (7 types)

#	Exception	Symptom	Cause	Resolution
1	Instruction creation failure	AsbBstCreateJob errors	Parameter exception / Mandate not Authorised	Check Mandate status and request parameters
2	Polling timeout	Still PENDING after 60 polls	Bank processing anomaly	Manually query bank-side status
3	Deposit failure	Status becomes FAILED	Bank rejected (insufficient balance/limit etc.)	Check bank-returned error code
4	Deposit refund	Status becomes REFUNDED	Bank initiated refund	Reverse credited funds, notify user
5	Bank-side deposit not synced	source=2 deposit moomoo didn't receive	Callback lost	Manually query Airstar API to supplement
6	Amount mismatch	Credited amount differs from requested amount	Bank-side fees or exchange rate difference	Verify bank-side transaction details
7	Duplicate deposit	Same deposit created multiple records	Deduplication mechanism failed	Check procedure_id/request_id/bank_ref_id

Withdrawal Exceptions (5 types)

#	Exception	Symptom	Cause	Resolution
1	Withdrawal instruction failure	AsbBstTransfer errors	Parameter exception / Bank rejected	Check error code, release frozen funds
2	Polling timeout	Still PENDING after 10 polls	Bank processing anomaly	Manually query bank-side status
3	Freeze not released	Withdrawal failed but funds still frozen	Release process exception	Manually release freeze
4	Bank-side withdrawal not synced	User initiated withdrawal from bank side but moomoo didn't deduct	Callback lost	Manually query Airstar API, execute deduction
5	Partial withdrawal	Bank only transferred partial amount	Bank-side limit or insufficient balance	Verify amount difference, process remainder

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Monitoring & Alerts

Airstar 13 Alert Items

#	Alert Item	Trigger Condition	Severity	Response
1	Authorization creation timeout	Mandate in PendingAuthorise exceeds threshold	High	Check Airstar API connectivity
2	Authorization failure rate spike	RejectAuthorise count exceeds limit per time unit	High	Investigate bank-side anomaly
3	Deposit creation failure	AsbBstCreateJob consecutive failures	High	Check request parameters and API status
4	Deposit polling timeout	AsbBstCreateResultJob entered slow poll with no terminal state	High	Manually query bank-side status
5	Deposit refund	Received REFUNDED status	High	Immediately reverse, notify user
6	Withdrawal polling timeout	AsbBstTransfer exhausted 10 attempts	High	Manually confirm bank-side status
7	Bank-side withdrawal pull exception	SyncAsbBstWithdraw cron errors	Critical	Check Airstar API connectivity
8	Freeze not released	Withdrawal failed but freeze not rolled back	Critical	Manually release freeze
9	Daily circuit breaker triggered	Daily cumulative reaches stop threshold	Medium	Operations confirms then decides whether to restore
10	Cumulative alarm triggered	Cumulative reaches alarm threshold	Medium	Operations monitors, assess risk
11	Duplicate transaction detected	procedure_id/request_id duplicate	High	Check deduplication logic
12	API connectivity exception	Airstar API response timeout or error rate increase	Critical	Contact Airstar Bank technical support
13	Bank-side initiation volume anomaly	source=2 transaction volume spike	Medium	Investigate whether normal business fluctuation

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Error Codes

Error Code System

Airstar error codes are categorized by operation type prefix, not by business domain:

Error Code Prefix	Operation Type	Description
14060xxxx	Create authorization	Errors when moomoo initiates Mandate creation
14061xxxx	Cancel authorization	Errors when moomoo initiates Mandate cancellation
14062xxxx	Query authorization	Errors when moomoo queries Mandate status
14063xxxx	moomoo-initiated transfer	Errors when moomoo initiates deposit/withdrawal transfer
14064xxxx	Query transfer	Errors when moomoo queries transfer status
14067xxxx	Bank-initiated transfer	moomoo-side validation errors when bank initiates transfer
14072xxxx	Notify transfer result	Errors when bank notifies transfer result
14073xxxx	Notify authorization result	Errors when bank notifies authorization result

CMB/CMBC Error Codes

CMB and CMBC return result codes via Socket callback (0/-5/-6) and do not have independent error code series. Detailed callback handling logic is at Withdrawal Data Dictionary - Bank Callback Result Codes.

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BST Channel Comparison

Airstar vs CMB/CMBC

Dimension	Airstar	CMB / CMBC
Protocol	REST API (HTTP + JSON)	Socket binary protocol
Encoding	UTF-8	GB18030
Initiator	moomoo + bank bidirectional	CMB bidirectional / CMBC bank-side only
Authorization Model	Mandate (6 states)	BST Agreement (2 states)
Multi-market Mapping	One authorization -> 3 markets auto-mapped	Separate agreement per market
Core Identifier	mandate_id	Bank card number
Result Delivery	Polling	Real-time push (Socket callback)
Deposit Status	NEW/PENDING/SUCCESS/FAILED/REFUNDED	Success/Failure
Withdrawal Status	NEW/PENDING/SUCCESS/FAILED	0 (Success)/-5 (Timeout)/-6 (Rejected)
Deposit Polling	60 fast polls + slow poll	No polling needed
Withdrawal Polling	10 times	No polling needed
Refund Mechanism	Supports REFUNDED status	None
Online Account Opening	Supports three-in-one	Not supported
Error Codes	By operation type (14060~14073 series)	0 / -5 / -6

BST vs Other Withdrawal Channels

Dimension	BST	Online Banking (HSBC/Hang Seng)	FPS	Traditional Channels
Automation	Fully automatic (only one)	Semi-auto	Semi-auto	Manual
Speed	Seconds~minutes	Minutes~hours	Minutes	Hours~days
Protocol Complexity	High (Socket/API)	Low (Corporate online banking)	Medium (FPS API)	Low (Online banking/wire)
Operations Involvement	Only on exceptions	Confirm step	Confirm step	Full involvement
Applicable Banks	CMB/CMBC/Airstar	HSBC/Hang Seng	BOCHK/SCB/CGB	All banks
Limit Control	Three-tier limit system	Bank-side limits	FPS system limits	Varies by bank

After Reading

I want to...	Go to
Deep dive into CMB's Socket binary protocol	CMB
Deep dive into CMBC's XML text protocol	CMBC (MS)
Deep dive into Airstar's REST API + RSA-OAEP	Airstar
See BST's role in the withdrawal system	Withdrawal Methods Overview
See auto-withdrawal 6 conditions and three-tier limits	Withdrawal Rules Manual
Look up Mandate status codes and Airstar error codes	Unified Error Code Center
See BST job frequencies and alerts	Cron Jobs & Monitoring
See other banks' integration methods	Bank Capability Matrix

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