By Why Stocks Halt: Limit Up-Limit Down Bands
Why stocks halt? Limit up-limit down bands dey pause trading for five minutes when price pass rolling reference. See how bands work and wetin happen to orders.
Stocks fit halt for five minutes under one rule wey dem dey call limit up-limit down: when price pass one band wey dem set around the stock recent average, trading stop for every venue at the same time. Imagine say one small-cap stock don rise 30 percent by middle morning. Quote stop to update, the last print remain, and five-minute clock start. This page explain how dem build those bands, how wide dem be for each price level, and wetin happen to resting order while the tape dark.
Wetin you dey see when stock halt
Na the stock primary listing exchange dey declare limit up-limit down pause, and every other venue honor am for that same moment. For five minutes, no execution fit happen anywhere. Broker screen fit still show the last trade, but that number don stale, or quote wey one side dey miss.
Two things make this pause different from every other reason ticker fit go quiet. Na automatic process, so no human dey decide say the stock need break. And the plan itself fix am at five minutes. The tape carry special halt code for volatility pause, separate from codes for news and market-wide events.
Where limit up-limit down rule come from
On May 6, 2010, prices across the US market fall and recover within few minutes. Trades print for levels wey far from where dem quote those same names moments before. Our 2010 flash crash breakdown explain wetin happen that afternoon. Single-stock circuit breakers arrive within weeks. Limit up-limit down plan replace dem in 2012, first as pilot before dem make am permanent in 2019.
Wetin be limit up-limit down price bands?
The band na percentage around reference price. That reference price na the average of eligible trade prices for the previous five minutes, refreshed at least every 30 seconds. E dey roll. Na this part most readers dey get wrong: dem no measure the band from yesterday close. Stock wey dey rise steadily all morning dey pull its own reference price up, and the band dey move along underneath. Stock wey jump within one second go meet the band still near where e trade moments earlier. Quotes outside the band no fit display or execute, so venues either reprice aggressive limit order to the band edge or reject am.
How far fit stock move inside five minutes? The panel below measure every five-minute window of the regular session over the past year for eight names. E take the full high-to-low move inside each window.
The exact SQL behind every number
SELECT
ticker,
round(quantileDeterministic(0.999)(range_pct, det), 2) AS p999_range_pct,
round(max(range_pct), 2) AS max_range_pct,
count() AS window_count
FROM
(
SELECT
ticker,
toStartOfFiveMinute(window_start) AS bucket,
toUnixTimestamp(toStartOfFiveMinute(window_start)) AS det,
(toFloat64(max(high)) - toFloat64(min(low)))
/ toFloat64(argMin(open, window_start)) * 100 AS range_pct
FROM global_markets.delayed_stocks_minute_aggs
WHERE ticker IN ('SPY', 'KO', 'AAPL', 'MSFT', 'NVDA', 'TSLA', 'COIN', 'MSTR')
AND window_start >= today() - 370
AND window_start < today() - 2
AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60
+ toMinute(toTimeZone(window_start, 'America/New_York'))) >= 570
AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60
+ toMinute(toTimeZone(window_start, 'America/New_York'))) < 960
GROUP BY ticker, bucket, det
HAVING min(low) > 0
)
GROUP BY ticker
ORDER BY max_range_pct DESCOver the past year, COIN post the widest five-minute move in the group, at 6.4 percent of the price at the start of that window. Its 99.9th percentile window cover 3.1 percent. So even for the loudest name here, 999 windows out of every 1000 stay inside that figure. For the quiet end, AAPL never pass 2.15 percent across 19586 windows. A 5 percent band no come close to normal five-minute movement. Dem build am for outlier moves.
How wide the limit up-limit down band dey?
Band width depend on the security tier and its price. The plan divide every national market system stock into two tiers, and the percentage become wider as price fall:
- Tier 1, wey cover S&P 500 members, Russell 1000 members and selected exchange traded products, with price above $3.00: 5 percent.
- Tier 2, meaning every other listed stock with price above $3.00: 10 percent.
- Any stock priced from $0.75 to $3.00: 20 percent.
- Any stock priced below $0.75: the lesser of 75 percent or $0.15.
The exchanges wey run the plan dey amend the tier lists and exact schedule from time to time. So treat the structure above as the shape of the rule, no be permanent table. The main mechanic remain the same: percentage of rolling five-minute average, with wider band for cheaper names. That same percentage give very different dollar cushion depending on where stock dey trade.
The exact SQL behind every number
SELECT
ticker,
round(toFloat64(argMax(close, window_start)), 2) AS last_price,
round(toFloat64(argMax(close, window_start)) * 0.05, 2) AS band_5pct_dollars,
round(toFloat64(argMax(close, window_start)) * 0.10, 2) AS band_10pct_dollars
FROM global_markets.delayed_stocks_minute_aggs
WHERE ticker IN ('SPY', 'MSFT', 'AAPL', 'TSLA', 'NVDA', 'KO', 'PLTR', 'F')
AND window_start >= today() - 10
AND volume > 0
GROUP BY ticker
ORDER BY last_price DESCA 5 percent band on SPY near $767.96 give $38.4 room for either direction before quote reach the edge, and $76.8 inside the doubled windows wey we describe below. The same 5 percent on F near $13.96 na $0.7. One determined order fit cover that distance. Na why the percentage dey widen as prices fall.
Price zones matter pass as dem look, because plenty symbols for the tape dey trade for the cheap end.
The exact SQL behind every number
SELECT
price_zone,
stock_count,
round(stock_count * 100.0 / sum(stock_count) OVER (), 1) AS share_of_tape_pct
FROM
(
SELECT
multiIf(last_price < 0.75, 'under $0.75',
last_price < 3, '$0.75 to $3',
last_price < 20, '$3 to $20',
last_price < 100, '$20 to $100',
last_price < 500, '$100 to $500',
'$500 and up') AS price_zone,
count() AS stock_count
FROM
(
SELECT
ticker,
toFloat64(argMax(close, window_start)) AS last_price
FROM global_markets.delayed_stocks_minute_aggs
WHERE window_start >= today() - 8
AND window_start < today() - 1
AND volume > 0
GROUP BY ticker
HAVING last_price > 0
)
GROUP BY price_zone
)
ORDER BY multiIf(price_zone = 'under $0.75', 1,
price_zone = '$0.75 to $3', 2,
price_zone = '$3 to $20', 3,
price_zone = '$20 to $100', 4,
price_zone = '$100 to $500', 5,
6)Among symbols wey print trade during the past week, 728 last trade under $0.75 and 949 between $0.75 and $3.00. Na these two zones carry the widest percentage bands. The $20 to $100 zone hold 50.4 percent of the list. The plan cover national market system securities, so the very cheapest part of this population dey outside am. Cheap names get wider band in percentage terms but narrower band in cents. Na deliberate trade-off for the plan.
Why the bands double for open and close
From 9:30 to 9:45 a.m. ET, and again from 3:35 p.m. to the 4:00 p.m. close, every band double. Tier 1 move from 5 percent to 10, while Tier 2 move from 10 to 20. Those two windows get the strongest price discovery of the day. Band wey fit midday conditions go pause ordinary names every session.
The exact SQL behind every number
SELECT
formatDateTime(toStartOfInterval(toTimeZone(window_start, 'America/New_York'), INTERVAL 15 MINUTE), '%H:%i') AS et_time,
round(avg((toFloat64(high) - toFloat64(low)) / toFloat64(open) * 100), 3) AS avg_minute_range_pct,
round(quantileDeterministic(0.99)((toFloat64(high) - toFloat64(low)) / toFloat64(open) * 100,
toUnixTimestamp(window_start)), 3) AS p99_minute_range_pct
FROM global_markets.delayed_stocks_minute_aggs
WHERE ticker IN ('SPY', 'AAPL', 'MSFT', 'NVDA', 'TSLA')
AND window_start >= today() - 200
AND window_start < today() - 2
AND open > 0
AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60
+ toMinute(toTimeZone(window_start, 'America/New_York'))) >= 570
AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60
+ toMinute(toTimeZone(window_start, 'America/New_York'))) < 960
GROUP BY et_time
ORDER BY et_timeAcross five liquid names during the past several months, the average minute inside the 09:30 bucket cover 0.288 percent from high to low, compared with 0.087 percent inside the 12:30 bucket. The final bucket of the day, 15:45, run at 0.117 percent. The 99th percentile minute follow the same curve at a higher level, and the doubled bands sit above the two peaks. Quoted spreads follow that daily pattern too, as we cover for why spreads dey widen for open.
Limit state, straddle state, and the fifteen-second rule
Limit state start when the best offer for the market sit exactly at the lower band without crossing the best bid, or when the best bid sit exactly at the upper band without crossing the best offer. Price don pin for the edge. Trading continue inside the band while this condition last. The clock na the important part: if quote no step out of limit state within 15 seconds, the listing exchange declare the five-minute pause.
Most limit states no reach that point. Liquidity show for the band edge, quote step back inside, and the fifteen seconds no elapse. Na how one name fit touch its bands again and again during violent session but get only one or two actual halts.
Straddle state get another shape. Best bid sit below lower band, or best offer sit above upper band, so quote straddle the band range instead of pinning at one edge. E fit happen when related market dey move faster than the stock own reference price fit follow. Straddle state no produce automatic pause. The listing exchange fit declare one if trading for that security no dey happen for 15 seconds.
How LULD different from circuit breakers and news halts
Market-wide circuit breakers watch one number: S&P 500 against the previous day close. Then dem stop everything at once. Level 1 decline of 7 percent or Level 2 decline of 13 percent halt all US equity trading for 15 minutes when e happen before 3:25 p.m. ET. Level 3 decline of 20 percent end the session at any hour. Those thresholds apply to the index and dem rarely reach am. Limit up-limit down apply to individual stock and fit trigger somewhere in the market on most days. Automated systems need handle both types, and circuit breakers for trading bots explain how.
Regulatory halts different again. For Nasdaq-listed name, code T1 mean halt because company news dey pending, while T12 mean halt while exchange dey request extra information from company. Person dey declare these halts. Dem last as long as exchange require, no be five minutes, and stock often reopen far from the last print. Names wey spend part of the week halted dey show regularly among the biggest stock movers this week.
Wetin happen to your orders during five-minute pause
Nothing execute while the pause dey run. After that, behavior depend on venue and order type. Broker own documentation na the place to confirm the details.
- Resting limit orders generally remain for the book, though some exchanges cancel market orders and certain time-sensitive types once halt start.
- You fit usually enter or cancel new orders during the pause, and dem queue for reopening.
- Limit order wey price pass the band no fit display there. Venue fit move am to the band edge or reject am.
- Stop order elect on a print, and no print happen during pause. When reopening auction print, elected stop become market order into whatever price the auction set. That price fit far from the stop price.
The primary listing exchange run the reopening as auction. Orders collect on both sides while exchange publish indicative prices. Then one crossing price print all the accumulated interest at once. The mechanics match day opening, as we cover for wetin be opening auction. If listing exchange no fit reopen within 10 minutes, other exchanges fit resume trading for the name.
FAQ
Why stocks dey halt for five minutes?
Five-minute halt na the limit up-limit down volatility pause. When stock best bid or best offer sit for the edge of its price band for 15 straight seconds, primary listing exchange stop trading for five minutes. Then e reopen with auction.
How wide the limit up-limit down band dey?
Na percentage of rolling five-minute average price: 5 percent for large index-member names above $3.00, 10 percent for other listed stocks above $3.00, 20 percent between $0.75 and $3.00, and the lesser of 75 percent or $0.15 below that. Each one double during the first 15 minutes and final 25 minutes of the session.
You fit buy or sell stock while e halt?
No trade execute during halt. Most venues let you place or cancel orders while pause dey run, and those orders join the reopening auction. But some order types dey cancel automatically once halt start.
Wetin be the difference between trading halt and circuit breaker?
Limit up-limit down halt apply to one stock and last five minutes. Market-wide circuit breaker apply to every US equity at once. E follow S&P 500 decline from previous close, at levels of 7, 13 and 20 percent.
Halt mean say something wrong with company?
No, not by itself. Volatility pause measure price movement over five minutes and nothing else. Regulatory halt, marked T1 or T12 for Nasdaq-listed name, na different matter. Exchange declare am because of pending news or request for information.
Every panel here come with the SQL wey produce am, and you fit expand am under the chart. To see how close a name wey you dey follow don come to its own bands, ask the question in plain English on the Strasmore terminal.