The correct answer is A . Margin requirements are a fundamental credit- and market-risk control applying to both long and short positions . Their purpose is to ensure that sufficient client equity or collateral is maintained relative to the market exposure generated by the position. Although “cover losses” is simplified exam wording, A most accurately reflects the risk-management function of margin.

CIRO IDPC Rule 5113 specifically establishes calculations for “long and short positions in client accounts.” For a long position, loan value is generally determined using the market value less the applicable margin percentage. For a short position, the calculation recognizes the additional resources required because the client has sold securities not owned and must ultimately cover the short position. If the resulting account loan value becomes deficient, the account must be brought into good standing through the required margin.

B is incorrect because margin expressly applies to long as well as short positions. C is incorrect because discretionary authority does not remove regulatory margin requirements. D is incorrect because increasing the required client equity reduces the amount that can be financed and therefore limits leverage , which is one of margin's principal risk-control effects.

The CIRE curriculum specifically requires candidates to understand margin's purpose, general application, and impact of short and long positions .

Study Guide Reference: CIRE Element 6.10 — Margin Requirements; IDPC Rule 5113.

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