Quick Answer
Trader mandates define and limit trading authority. Independent aggregation units permit separate netting for short-sale marking when four conditions are met: a written plan supporting independent identity, net positions at each sale, independent strategies, and one unit per trader at a time. Firm-wide netting is the default; sham transfers or assignments cannot justify a long mark.
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 |
|---|---|
| Written plan | Identifies each unit, specifies its objectives, and supports its independent identity |
| Sale-time netting | Each unit determines its net position in every security it trades at each sale |
| Independent strategy | Traders pursue only the unit's objectives or strategies and do not coordinate that strategy with another unit |
| Single-unit assignment | Each individual trader is assigned to only one unit at any time |
Physical barriers, reporting lines, and unit-level accounting can support the controls, but none substitutes for these conditions. Shared operations staff or a consolidated firm profit report does not by itself defeat independent treatment.
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 elects and qualifies for independent aggregation, it uses the unit's net position. Otherwise, the default is firm-wide netting. A qualifying unit long 1,000 shares can support a 500-share long sale despite another unit's short position, provided the other long-marking and delivery conditions are met.
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.
- The written plan must identify each unit and support its independence. One plan may cover several units. A generic mention of aggregation units is insufficient.
What Should You Check on Exam Day?
- Can you state the written-plan, sale-time netting, independent-strategy, and single-unit assignment conditions?
- Do you know that a trader mandate must be both written and enforced, and that documentation alone does not satisfy supervision?
- Can you state why a trader who flips between aggregation units to mark a short sale as long commits a Reg SHO violation?
- Can you distinguish elected independent-unit treatment from default firm-wide netting?