Limit Up Limit Down Orders¶
OVERVIEW¶
A Limit Up Limit Down (LULD) order is a trade execution governed by the SEC's LULD rule, which automatically pauses trading in a security when its price moves outside dynamically calculated price bands. The mechanism replaced single-stock circuit breakers in 2013 to prevent erroneous price dislocations caused by algorithmic trading or high-frequency anomalies.
Note
Traders do not explicitly route "LULD orders." The LULD rule acts as a structural filter applied to all routed market and marketable limit orders across every participant on the exchange.
Orders submitted during an LULD pause are rejected or queued until trading resumes at a price within the allowable bands.
FEATURES¶
Price Band Calculation¶
LULD bands are derived from a reference price, defined as the arithmetic mean of executed prices over the preceding five-minute window. If no recent trades exist, the primary listing exchange's last sale price is used instead.
Band formulas:
| Band | Formula |
|---|---|
| Upper Band | Reference Price × (1 + Threshold %) |
| Lower Band | Reference Price × (1 − Threshold %) |
Security Tiers¶
Securities are categorized into tiers with distinct percentage thresholds:
| Tier | Eligible Securities | Band Width |
|---|---|---|
| Tier 1 | S&P 500, Russell 1000, select ETFs | ±5% |
| Tier 2 | All other NMS stocks | ±10% |
| Tier 3 | Select ETFs | ±20% |
Halt Trigger and Duration¶
| Parameter | Value |
|---|---|
| Breach window before halt | 15 seconds |
| Trading pause duration | 5 minutes |
| Resumption method | Price auction within new bands |
Tip
Monitor LULD bands in real time on Tapeboard using the Band Overlay toggle in the order entry panel. Algorithms that route into an imminent halt are flagged with a yellow band-breach warning before submission.
HOW TO USE¶
1. View current LULD bands Open any equity quote on Tapeboard. The upper and lower LULD bands are displayed as dashed horizontal lines on the price ladder and the chart band overlay.
2. Understand halt status When a halt is active, the order entry panel displays a red LULD HALT badge. Orders queued during the halt are held in the pending queue and released automatically when trading resumes.
3. Interpret resumption auctions After a five-minute pause, the primary exchange runs a price auction. The clearing price must fall within the newly recalculated bands. Tapeboard displays the indicative auction price in the status bar during the halt window.
4. Avoid rolling halts If a stock resumes and immediately breaches the new bands again, a rolling halt cascade can occur. Watch for this pattern when fundamental news has gapped a stock far from its prior reference price.
Note
An LULD halt does not guarantee a price reversal. The resumption auction can clear at a materially different level from the pre-halt price, provided it falls within the updated bands.
KEYBOARD SHORTCUTS¶
| Action | Shortcut |
|---|---|
| Toggle LULD band overlay on chart | Shift + L |
| Open LULD halt log for current symbol | Ctrl + H |
| Jump to next halted security in watchlist | Alt + ↓ |
| Dismiss halt badge and acknowledge status | Esc |