A risk limit is a venue-defined constraint on permitted exposure or the margin required to support it. In derivatives interfaces, the term often refers to a tiered schedule linking position value with initial margin, maintenance margin and maximum leverage. It is not a personal stop-loss target.
Why larger exposure can require more support
A larger position can be harder to close without moving the market. Risk tiers may therefore require more collateral or lower maximum leverage as exposure grows. The schedule can consider existing positions and active orders that would increase them.
A trader can encounter an order rejection even with cash remaining if the requested exposure exceeds the allowed limit for the current settings. Reducing leverage may make a larger tier available but can also increase required margin. The exact interaction depends on the product and account mode.
Limits can change without a new trade
When limits are measured by value, price movements can alter the assessed exposure even if contract quantity is unchanged. Venues can also revise parameters as market conditions change, with their own implementation procedures.
A risk-tier limit differs from a maximum single-order size or a separate account position cap. Portfolio-margin systems may use another risk framework entirely. Checking the current parameter table, its valuation basis and how pending orders count is necessary to understand which constraint is binding.