Trader Mandates and Aggregation Units
Quick Answer
A trader mandate is the written grant of authority that defines what a trader may do (products, position limits, loss limits, counterparties, trading hours, prohibited strategies). An aggregation unit under Reg SHO is a defined trading unit whose long and short positions are netted separately from the rest of the firm for short-sale marking. The principal must enforce the mandate, monitor for breaches, and ensure traders cannot move between aggregation units to defeat the netting requirement. A bona fide aggregation unit needs a clear trading objective, non-commingled positions, a written plan, and physically or functionally separated traders.
The supervisory structure begins before any order is entered. A firm controls trader behavior through written mandates that limit the scope of authority, and it isolates trading desks through aggregation units so that a long position on one desk does not artificially offset a short position on another. Both controls are foundational because every other rule in this unit (locate, close-out, Manning, best execution) presumes the firm knows who is authorized to trade and where their positions sit.
Trader Mandates
A trader mandate is a written authorization defining the perimeter of each trader's activity. The mandate must be implemented and enforced, not merely documented.
The mandate scope must address:
- Products allowed (e.g., NMS equities, listed options, corporate bonds, foreign exchange)
- Position limits (gross and net, by product and aggregate)
- Loss limits (daily, weekly, drawdown)
- Delta or notional limits for derivatives books
- Counterparties approved for trading
- Trading hours (regular session, extended hours, overnight)
- Prohibited strategies (e.g., naked shorts, exotic structured products)
The principal supervising the trading desk must:
- Monitor for breaches through real-time or end-of-day exception reports
- Escalate when a limit is exceeded, including notifying the CCO and the trader's direct supervisor
- Document the breach, the response, and any required corrective action
Think of it this way: A trader mandate is the trading-desk equivalent of a registered representative's customer agreement. The mandate is what gives the firm written grounds to discipline a trader who exceeds authority, the same way customer paperwork gives the firm grounds to enforce the terms of an account. Without a mandate, an unauthorized trade is hard to challenge after the fact.
Exam Tip: Gotchas
- A mandate must be in writing AND enforced. A firm that drafts a mandate but never reviews exception reports has not satisfied the supervisory obligation. Documentation alone is insufficient.
- Mandate breaches must be escalated, not unwound and ignored. A firm that lets the trader close a position in excess of the limit without compliance review converts a one-time breach into a documented pattern of inaction by the supervisor.
Aggregation Units Under Reg SHO
A large broker-dealer typically has multiple trading desks running independent strategies. Reg SHO allows the firm to net long and short positions separately at the desk level rather than firm-wide for short-sale marking purposes. This is the aggregation unit structure.
A trading desk qualifies as a bona fide aggregation unit only if all four conditions are met:
| Condition | Requirement |
|---|---|
| Clearly defined trading objective | The unit has a distinct strategy, mandate, or business purpose (e.g., market making in tech-sector ETPs, statistical arbitrage in financial-sector equities) |
| Non-commingled positions | The unit's positions are not mixed with any other unit's positions for ownership, P&L, or settlement purposes |
| Written plan | A written document describes the unit, its objective, the participating traders, the positions it holds, and how it operates |
| Trader separation | Each trader assigned to the unit is physically separated from traders in other units OR clearly identified by distinct functional reporting lines |
The principal must ensure that:
- Traders are assigned to a specific unit and do not trade outside their unit
- Positions are not transferred between units in a way that defeats the netting requirement
- Any reassignment of a trader follows the firm's written process and is documented
Why Aggregation Units Matter for Short-Sale Marking
When a firm marks a sell order as long under Reg SHO, the determination is made at the aggregation unit level, not firm-wide. A unit that is long 1,000 shares of XYZ can mark a 500-share sale as long, even if a separate aggregation unit at the same firm is short 10,000 shares of XYZ.
Think of it this way: Aggregation units treat a large firm's trading desks like separate broker-dealers for short-sale purposes. Desk A and Desk B can hold opposite positions in the same security and mark their orders independently. The firm trade-blotters reflect each desk's position; the netting is intentionally not consolidated.
Exam Tip: Gotchas
- A trader who flips between aggregation units to mark a sale "long-from-short" is committing a Reg SHO violation. The unit must be bona fide. Reassignment for the purpose of marking a covered short as long is a sham aggregation that triggers both the Reg SHO aggregation-unit framework and the publication-of-transactions manipulation prohibition.
- Aggregation unit determinations are at the unit level, not the firm level. A firm that is net long across all desks but has a short-only desk must mark that desk's sales as short, even though the firm is long overall.
- Each aggregation unit needs its own written plan. A general firm-wide policy mentioning "aggregation units" does not satisfy the requirement. Each unit must be specifically described.