LULD Halt¶
OVERVIEW¶
An LULD (Limit Up / Limit Down) halt is a 5-minute trading pause triggered automatically when a stock's price exits a predetermined band around its rolling 5-minute reference price. Introduced in 2013, LULD replaced the legacy single-stock circuit breaker and is now the most common intraday trading halt in US equities.
Note
Tapeboard's halt feed tracks LULD halts in real time and frequently logs the same symbol halting 5–10 times within a single session.
HOW LULD BANDS WORK¶
Bands are assigned by tier based on the security's classification. All bands double in width during the opening 15 minutes and closing 25 minutes of the regular session.
| Tier | Securities | Band Width |
|---|---|---|
| Tier 1 | S&P 500, Russell 1000, select large-cap ETFs | ±5% |
| Tier 2 | All other securities above $3 | ±10% |
| Sub-$3 | Stocks priced below $3 | ±20% |
The band is centered on a rolling 5-minute VWAP of consolidated trades.
Halt trigger sequence:
- The National Best Bid (downside) or National Best Offer (upside) exits the band.
- The price remains outside the band for 15 consecutive seconds.
- A 5-minute halt is imposed.
- A re-opening auction determines the resumption price.
Tip
The resumption auction can produce a significant gap from the pre-halt price. Factor this into any position sizing around volatile names.
WHAT HAPPENS DURING AN LULD HALT¶
| Condition | Behavior |
|---|---|
| Resting orders | Remain on the book but cannot match |
| Market orders | Rejected with a halt-reject error code |
| Limit orders | Can be entered or cancelled; will not fill until halt clears |
| Options on halted underlying | Also paused for the halt duration |
| Resumption price | Set by re-opening auction; may gap from pre-halt level |
WORKED EXAMPLE¶
The following example illustrates a typical LULD sequence for a small-cap stock trading at $10 under Tier 2 rules (±10% band = $9.00–$11.00):
| Time (ET) | Event |
|---|---|
| 09:35:00 | Stock spikes to $11.50 — offer exits the ±10% band |
| 09:35:15 | 15 consecutive seconds outside the band; LULD halt triggers |
| 09:40:00 | Re-opening auction prints at $11.20 within the recalculated band |
| 09:40:00+ | Trading resumes with a fresh 5-minute reference price |
Note
Stocks with high short interest and low float are disproportionately affected. Squeeze dynamics can drive prices through bands rapidly and trigger multiple consecutive halts.
LULD VS. OTHER HALT TYPES¶
| Halt Type | Trigger | Scope | Automatic |
|---|---|---|---|
| LULD | Price exits percentage band for 15 seconds | Single stock | Yes |
| T1 | News pending; issuer-requested | Single stock | No |
| Circuit Breaker | S&P 500 index decline threshold | Market-wide | Yes |
| T12 | Regulatory action by exchange or SEC | Single stock | No |
LIMITATIONS AND COMMON MISCONCEPTIONS¶
Stop Orders Do Not Execute During a Halt
A stop-loss order rests unfilled for the entire halt duration and may execute at the resumption auction price — frequently several percentage points worse than the stop level. LULD halts provide no stop-loss protection.
LULD Halts Can Repeat Consecutively
If a stock re-enters the band immediately after resumption, a new 5-minute halt triggers. Multiple consecutive pauses on the same symbol in a single session are common and are logged individually in Tapeboard's halt feed.