Price limit rule — Firm restrictions tied to exchange price limits and unusual market conditions, such as limit-up or limit-down sessions.
How price limit rule works in prop trading
Exchanges halt or band trading when a product moves too far too fast. During those periods, simulated pricing can diverge from the real market and orders may not behave normally, so firms add rules covering them — commonly voiding profits earned during a limit condition, or prohibiting new positions until normal trading resumes.
There is usually a broader clause alongside it covering extreme conditions generally: exchange outages, platform failures, and severely dislocated pricing. It gives the firm discretion to void trades whose fills the real market would not have produced. Rare, but decisive when it applies, and worth reading before an event day.
Key points
- Applies during exchange limit-up, limit-down, and halt conditions.
- Profits earned during a limit condition may be voided rather than credited.
- Usually paired with a wider clause covering outages and dislocated pricing.
- The firm's discretion here is broad, which matters most around scheduled high-volatility events.
Also known as
- limit up limit down rule
- exchange price limit
- extreme market conditions
Frequently asked questions
What happens if the market goes limit up while I am in a trade?
Trading in the product halts or is banded at the limit, so you may be unable to exit. Depending on the firm's rules, profit or loss accrued during the limit condition may be adjusted or voided. Positions are still measured against your drawdown throughout.
Can prop firms void trades?
Yes, under defined circumstances — trades during exchange limit conditions, platform or data errors, or fills the firm judges could not have occurred in the live market. The circumstances are set out in the terms and this is the section to read closely.
Price limit rule is described here as a plain-language educational definition. Firms, platforms, and account programs may apply different conditions or calculations. Verify the current official terms before using this definition to make an account decision.