Trading halt API: Nasdaq halts and resumptions with reason codes
A trading halt is the purest signal that something is happening to a stock right now. Get Nasdaq halts and resumptions with reason codes about 20 seconds after the exchange posts them, tagged to the symbol, over REST or as a push feed.
Updated 2026-09-20 · 5 min read · every example runs against the live API
Halts are hard to source well: the exchange publishes them on a page with no per-item links, the reason codes are cryptic, and most news APIs do not carry them at all. The H1 News API turns Nasdaq's halt feed into ordinary articles — category=halts, source Nasdaq Trade Halts — so they flow through the same filters, the same stream and the same SDKs as everything else.
Today's halts
curl -H 'X-API-Key: YOUR_KEY' 'https://api.heliusone.com/v1/news/halts?date=today'{
"id": 597493,
"title": "Trading halt: UZX — Linkage Global Inc Cl A Ord Sh (NASDAQ, T1: news pending)",
"summary": "Halted 09/18/2026 15:50:00 ET. Reason T1: news pending.",
"url": "https://www.nasdaqtrader.com/trader.aspx?id=TradeHalts&symbol=UZX",
"source": "Nasdaq Trade Halts",
"type": "article",
"category": "halts",
"tickers": ["UZX"],
"sentiment": { "label": "neutral", "score": 0.0 },
"published_at": "2026-09-18T19:50:00+00:00",
"ingested_at": "2026-09-18T19:50:19+00:00"
}Three things to notice. The symbol is in tickers exactly — the tagger does not scan the text, it uses the exchange's symbol field. The reason code and its meaning are in the title. And published_at is the halt instant from the exchange, in UTC, so ingested_at − published_at is your true latency.
Resumptions
When the exchange posts a resumption time, a second event arrives:
"title": "Trading resumption: UZX — Linkage Global Inc Cl A Ord Sh (NASDAQ, T1: news pending)",
"summary": "Halted 09/18/2026 15:50:00 ET. Reason T1: news pending. Resumes 09/18/2026 16:20:00 ET."Pair the two by symbol and halt time. A T1 halt with no resumption after twenty minutes is worth a look; a T1 followed by a resumption and an 8-K is a news event you can now read in full via category=filings.
As a push feed, with context
The useful alert is not "UZX halted" but "UZX halted, and here is what was published about it this morning". Two calls:
import asyncio
from h1news import AsyncH1News
async def main():
async with AsyncH1News("sk_...") as news: # Pro plan
async for halt in news.stream(categories=["halts"]):
sym = halt["tickers"][0]
# what was said about this name in the last few hours?
ctx = await news.news(sym, date="today", exclude_category=["halts"], limit=3)
print(halt["title"])
for a in ctx["results"]:
print(" ↳", a["sentiment"]["label"], a["source"], a["title"])
asyncio.run(main())The full version with Slack and Discord webhooks is examples/halt_sniper.py.
On the Basic plan
No stream, but since_id polling every 20 seconds costs about 4,300 calls a month — well inside the 20,000 quota:
from h1news import H1News
news = H1News("sk_...") # Basic plan
for halt in news.poll(category="halts", interval=20): # 4,300 calls/month
print(halt["title"])History for one name
curl -H 'X-API-Key: YOUR_KEY' 'https://api.heliusone.com/v1/news/halts?ticker=NVDA&date=last30days'Halts are stored like any article, so date=, since=/until= and pagination all apply, and Pro keys get the full archive.
Reason codes
| Code | Meaning | Typical follow-up |
|---|---|---|
T1 | News pending | A press release on the wire, then T2 |
T2 | News released | Resumption 15–30 minutes later |
T12 | Additional information requested by Nasdaq | Can last days; watch category=filings |
LUDP | Limit-up / limit-down volatility pause | Resumes in 5 minutes; often repeats |
H10 | SEC trading suspension | The SEC order appears in category=regulatory |
H4 / H9 / H11 | Non-compliance / not current in filings / regulatory concern | Delisting risk |
MWC1–3 | Market-wide circuit breaker | Everything halts |
Questions
- How fast do halts arrive?
- The Nasdaq Trader halt feed is on the 20-second polling tier, so a halt appears in the API within about 20 seconds of the exchange posting it. Each halt record carries the exchange's halt time as published_at and our ingest time as ingested_at, so you can measure the lag on your own feed.
- Which exchanges are covered?
- The feed is Nasdaq Trader's, which lists halts across Nasdaq-listed securities and UTP-reported halts on other venues, including market-wide circuit breakers. NYSE-specific halts appear when they are cross-reported; they are not pulled from NYSE's own list.
- What do the reason codes mean?
- T1 news pending, T2 news released, T5 single-stock pause, T6 extraordinary market activity, T12 additional information requested, H4 non-compliance, H9 not current in filings, H10 SEC trading suspension, H11 regulatory concern, LUDP limit-up/limit-down pause, MWC1–3 market-wide circuit breakers. The code and its meaning are both in the title.
- Is a resumption a separate event?
- Yes. When Nasdaq publishes a resumption time the API emits a new article titled "Trading resumption: …" with the resume time in the summary, so a halt and its resumption are two events you can pair by ticker and halt time.
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