LULD Halt Calculator
Limit up / limit down bands for US equities. Enter a reference price and get the exact levels where trading goes into a limit state — and the price that triggers a 5-minute volatility pause.
How the bands are actually set
Limit up-limit down (LULD) is the national market system plan that replaced single-stock circuit breakers in 2013. It does not look at the last print or the previous close. It uses a reference price: the arithmetic mean of every eligible trade in the security over the preceding five minutes. That reference price is refreshed roughly every 30 seconds, so the bands trail a fast-moving stock rather than pinning it to where it opened.
Around that reference price the plan draws a percentage band. The percentage depends on two things only — which tier the security is in, and how much it costs.
| Reference price | Tier 1 | Tier 2 | 9:30–9:45 & 15:35–16:00 |
|---|---|---|---|
| Above $3.00 | 5% | 10% | Doubled (10% / 20%) |
| $0.75 to $3.00 | 20% | 20% | Doubled (40%) |
| Below $0.75 | Lesser of 75% or $0.15 | Doubled | |
Tier 1 is the S&P 500, the Russell 1000 and a published list of exchange-traded products. Everything else NMS is Tier 2. For a leveraged ETP the percentage is multiplied by the leverage ratio, so a 3x fund gets a 30% band where its 1x sibling gets 10%. Bands only exist during regular trading hours — there is no LULD in pre-market or after-hours, which is exactly why overnight news gaps straight through levels that would have paused it at 10:00.
Limit state, straddle state, and the 5-minute pause
Hitting the band is not the halt. Three distinct things can happen, and traders routinely confuse them:
1. Limit state
The national best offer drops to the lower band (or the national best bid rises to the upper band) and stays there. Trading continues, but only at or inside the band — nothing may print through it. The tape shows the security as limit up or limit down.
2. Exit within 15 seconds → nothing happens
If the quote moves back inside the band within 15 continuous seconds, the limit state simply ends. No halt, no pause, no code on the halt feed. This is the common case and it is why a stock can print a violent candle and never actually stop trading.
3. Fifteen seconds elapse → LUDP, five minutes
If the security is still in a limit state after 15 seconds, the primary listing exchange declares a trading pause: halt code LUDP. It lasts five minutes, then the exchange runs a re-opening auction. If it cannot reopen — usually because there is no valid auction price inside the new bands — the pause can be extended in further five-minute increments.
Straddle state (LUDS on some feeds) is the odd cousin: the NBBO is not itself at a band, but the band on the away side is inside the NBBO, so quotes on one side are unexecutable. It does not automatically pause; the listing exchange may declare a pause if it judges the situation harmful to a fair and orderly market.
LULD is not the market-wide circuit breaker
A LULD pause is one stock. A market-wide circuit breaker (MWCB) is the entire tape, triggered off the S&P 500 against the prior day's close:
| Level | S&P 500 decline | What happens |
|---|---|---|
| Level 1 | 7% | 15-minute market-wide halt (only if before 15:25 ET) |
| Level 2 | 13% | 15-minute market-wide halt (only if before 15:25 ET) |
| Level 3 | 20% | Trading stops for the rest of the day, any time |
Level 1 and Level 2 each trigger once per day. After 15:25 ET only a Level 3 breach stops the market — a 10% afternoon slide will keep trading while individual names pause on LULD underneath it.
Halt codes you will see next to a paused ticker
| Code | Meaning | News-driven? |
|---|---|---|
| LUDP | Volatility trading pause (this calculator) | Usually — a catalyst moved it through the band |
| LUDS | Volatility pause, straddle condition | Sometimes |
| T1 | News pending — the company has told the exchange something is coming | Always, and you do not know what yet |
| T2 | News released, dissemination in progress | Always |
| T12 | Exchange has requested additional information from the company | Often ugly |
| H10 | SEC trading suspension | Yes — and it is a 10-day suspension, not a pause |
| M | Market-wide circuit breaker | Macro |
The practical difference between LUDP and T1 is everything. A LUDP resumes in five minutes and the news is already public. A T1 resumes when the exchange says so and the news is not public yet — which is why the release timestamp on the wire is the only edge available. See what is hitting the wires right now →
Frequently asked
At what price will my stock halt?
Take the average trade price over the last five minutes, apply the band from the table above, and that is your limit up and limit down price. The calculator does it for you. The number moves as the stock moves — a stock that grinds up 30% over an hour never halts, because the reference price climbs with it. What halts a stock is speed, not distance.
Why did a stock halt on a 4% move?
Two likely reasons. Either it is a Tier 2 name below $3.00 in the opening period, where the numbers are unintuitive, or the reference price was stale relative to a very fast move. Check the tier first: a lot of retail traders assume every stock has a 10% band and misprice the risk on $2 names, where the real band is 20% (40% in the first fifteen minutes).
Does LULD apply pre-market or after hours?
No. The bands are only in force from 9:30 to 16:00 ET. Extended-hours sessions have no volatility pauses, which is precisely why an 8-K at 16:05 can move a stock 40% with nothing to stop it, and why the open the next morning is where the first pause happens.
How long does a LULD halt last?
Five minutes, then a re-opening auction. Expect longer in practice: if there is no valid auction price the pause extends in five-minute blocks, and heavily gapped small caps chain several pauses in a row. T1 news halts have no fixed length at all.
Can I trade during a LULD pause?
No trades execute in that security on any US venue during the pause, though orders can be entered and cancelled and the re-opening auction imbalance is published. Options on the underlying typically halt with it.
What is a straddle state, in plain English?
The quote is not at a band, but the band is sitting inside the quote, so one side cannot execute. It is a plumbing condition rather than a price condition, and it is the reason a stock sometimes appears frozen without any halt code appearing.
How do I find out why a stock halted?
The halt feed gives you a code, not a reason. For LUDP the reason is already on the wires — find the release that moved it. For T1, the release is coming and the whole game is seeing it the second it crosses. A consolidated real-time news feed covering the wires, regulators and filings is the only way to have the answer before the resumption auction: Top Tier Newswire pulls 40+ sources into one tape with sub-2-second latency, sentiment tagging and per-ticker watchlists. Free tier is delayed; Pro is real time.
Is this calculator official?
No. It implements the published percentage parameters of the LULD plan for reference and education. Your broker's and the listing exchange's numbers govern. Bands are rounded to the nearest penny by the processor, and reference prices are not public in real time, so treat these as very close approximations rather than exact levels.