Price Limit Rule
A rule restricting trading during exchange-imposed price limit halts (limit-up or limit-down moves) — typically required by firm risk policies during extreme volatility events.
What is Price Limit Rule?
The price limit rule governs how a prop firm handles trading during exchange-imposed price limit halts. Major futures contracts have daily move limits set by the exchange — typically 7%, 13%, and 20% for equity index futures — that trigger halts when reached.
When a price limit halt activates, the exchange suspends trading for a defined period (usually 15 minutes for the first level, 1 hour for subsequent). Orders cannot be placed, modified, or canceled during the halt. When trading resumes, the price often gaps significantly, producing extreme slippage on any pre-existing orders.
Prop firm rules during limit halts typically focus on three concerns: (1) preventing traders from being caught with positions across the halt and gap; (2) ensuring traders understand the gap risk if they hold positions through the halt; (3) allocating any forced losses across the firm’s trader population.
How Price Limit Rule works
CME equity index price limit triggers:
- Level 1 — 7% move: 15-minute halt. Reopens with current limit lifted.
- Level 2 — 13% move: Additional 15-minute halt.
- Level 3 — 20% move: Trading halted for the rest of the session.
Other contracts:
- Crude oil (CL): $10/barrel daily move limit
- Natural gas (NG): variable based on previous settlement
- Treasuries: typically 6 points (ZB) and 4 points (ZN)
Common firm policies during halts:
- No new entries: Trading platform may block new orders during halts
- Forced position closure: Some firms auto-flatten positions during halts to prevent gap exposure
- Position freezing: Existing positions held through halt; trader bears the gap risk on reopen
Why this matters for risk management: A trader long ES at 4500 right before a 7% limit-down halt could see ES gap to 4185 on reopen — a -$315 per contract / -$15,750 on a 5-contract position move. Far exceeding any prop firm’s drawdown buffer. This is why firms explicitly address limit halts in rule documentation.
Worked example
August 5, 2024 mini-flash crash example:
- Yen carry trade unwind triggered massive overnight selloff
- ES futures hit limit-down -7% in pre-market: 4925 → 4575
- 15-minute halt activated
- Reopen: gap to 4585 (slight bounce off limit) but volatile
- Most prop firm traders with overnight long ES positions had accounts closed by trailing drawdown breaches across the halt and reopen
- Some firms (Apex, TPT) issued statements waiving certain consistency-rule penalties for affected traders, but drawdown breaches stood
Operating around price limits:
- Don’t hold positions overnight when extreme volatility is anticipated (e.g., earnings season, central bank decisions, geopolitical shock days)
- Use stop losses positioned ABOVE/BELOW the daily limit thresholds — beyond a 7% move, your stop won’t fill at your set price anyway, but it acts as a margin-off-fault for risk modeling
- Read your firm’s specific limit-halt policy in advance — don’t try to find out during a halt
Price Limit Rule vs related concepts
Side-by-side comparison of Price Limit Rule against the most commonly confused alternatives.
| Concept | Definition | Category |
|---|---|---|
| Price Limit Rule this term | A rule restricting trading during exchange-imposed price limit halts (limit-up or limit-down moves) — typically required by firm risk policies during extreme volatility events. | Rules & Risk |
| Rule Breach | Any violation of a prop firm's trading rules — some breaches are warnings, others permanently end the account. | Rules & Risk |
| Max Drawdown | The total dollar amount your account can lose from its highest point (or starting balance) before the account is automatically closed. | Rules & Risk |
| Trailing Drawdown | A drawdown limit that follows your account's high water mark, tightening as you profit and capping your maximum loss from peak balance — the dominant risk model in the futures prop firm industry. | Rules & Risk |
| News Trading | A trading approach that takes positions around major economic news events — restricted, banned, or fully allowed depending on the prop firm. | Rules & Risk |
Why traders fail Price Limit Rule
Holding leveraged overnight positions through major events. Major events with overnight risk (FOMC, geopolitical crises, end-of-month flow events) can produce limit-down moves. Even a normal-sized intraday position becomes catastrophic if held through a limit halt.
Assuming stop losses will fill at the stop price during halts. They won’t. When trading reopens after a limit halt, your stop fills at the next available price — which can be substantially worse than your set level due to gap.
Trying to trade through halts. Most platforms block orders during halts. Trying to hit a buy at limit-down lows assuming you’ll catch the bounce typically results in either rejected orders or fills at much worse prices than expected.
Not knowing your firm’s halt policy. Each firm handles halts differently. Some auto-flatten. Some hold positions. Some have specific cooling-off periods. Read the firm’s documentation BEFORE you encounter a halt.
Frequently asked questions about Price Limit Rule
What happens if I hold a position through a price limit halt?
Trading suspends for 15+ minutes (depending on level). When it resumes, the price often gaps significantly. Your position is held through the gap — meaning you absorb whatever gap occurs on reopen. This can produce massive slippage on stop orders and severe drawdown.
Do prop firms close positions during limit halts?
Some do (auto-flatten policy), most don't (positions held through halt, trader absorbs gap risk). Each firm's policy varies — verify in advance, not during a halt event.
When does limit-down trigger on equity index futures?
CME equity index futures (ES, NQ, YM, RTY) trigger limit halts at 7% (15-min halt), 13% (additional halt), and 20% (full session halt) below the daily reference price. These are computed against the previous session settlement.
Can I trade during a limit halt?
No. The exchange suspends order entry, modification, and cancellation during halts. Most prop firm trading platforms reflect this — orders sent during halts are rejected. Wait for the halt to end before resuming trading.
How do I protect against limit halt risk?
Don't hold leveraged positions through known volatility events (FOMC, major geopolitical announcements, earnings on heavy-weight components). Use stop losses placed BEYOND likely limit thresholds as risk markers. Reduce position sizes during pre-event periods.