Market structure · 9 min read
Reg SHO explained: threshold lists, FTDs, and the 13-day misconception
Understand Reg SHO threshold-list criteria, failures to deliver (FTDs), listing dates, and the 13-day misconception. Compare SSR and locates; check original sources.
Reg SHO is short for Regulation SHO, a U.S. equity short-selling framework. A threshold list identifies securities meeting persistent delivery-failure criteria within that framework. Inclusion is neither a short-selling ban nor a prediction of a squeeze. Start with the criteria, dates, and evidence you can verify.
A stock moves sharply, and someone points out that it is “on Reg SHO.” A long run on the list soon becomes a story about forced covering and an imminent squeeze. Before accepting that story, pin down the observable fact: which official list, which date, and which security?
Reg SHO and the threshold list
Reg SHO is the common shorthand for Regulation SHO. Reg abbreviates Regulation; SHO identifies this set of rules. It covers U.S. equity short-sale marking, price restrictions, locates, and delivery-failure close-outs. “On Reg SHO” usually means appearing on a Threshold Securities List. The SEC’s Regulation SHO overview explains the wider framework.
A failure to deliver, or FTD, means securities were not delivered when due. Execution and completed settlement are separate events. Most U.S. stock trades have used a T+1 standard settlement cycle since May 28, 2024: generally the next business day after the trade. Do not carry old T+2 or T+3 assumptions into current research; see the SEC’s T+1 investor bulletin.
Reg SHO vs. SSR and locates: which rule does what?
| Rule or status | Main question | Continue reading |
|---|---|---|
| Rule 200: order marking | Should the order be marked long, short, or qualifying short exempt? | SEC framework overview |
| Rule 201: SSR | Where may certain short orders be displayed or executed after a trigger? | The SSR trigger, duration, and price test |
| Rule 203: locates and threshold requirements | Pre-sale borrow arrangements and threshold-security fail positions | Locates, HTB, and borrow costs |
| Rule 204: fail close-outs | Clearing participants’ obligations to address delivery failures | SEC close-out explanation |
These are different checks: SSR concerns short-sale pricing, a locate concerns borrow arrangements, and threshold membership concerns settlement. They may occur together or separately. Inclusion alone does not establish SSR status; hard-to-borrow status alone does not establish threshold membership.
What are the threshold-list inclusion and removal criteria?
For reporting securities covered by Regulation SHO, the Nasdaq definition requires five consecutive settlement days meeting the applicable thresholds: aggregate delivery failures at a registered clearing agency of at least 10,000 shares and at least 0.5% of the issuer’s total shares outstanding, with inclusion on an SRO list. The denominator is shares outstanding, not float; see Share price, market cap, and float for the distinction.
Removal also involves a consecutive-day condition: five settlement days below the applicable fail threshold. Calendar days are not settlement days.
OTC lists may also contain non-reporting securities covered by FINRA Rule 4320. Its conditions include at least 10,000 shares and a fail-position value of at least $50,000 under its valuation rules. Do not apply the 0.5% test indiscriminately to every OTC entry. Keep the source and rule designation.
What does inclusion establish?
It establishes threshold-list membership for the stated date. The SEC explains that delivery failures can arise from short sales, long sales, or processing delays. Inclusion alone does not establish illegal naked short selling.
| Observation | Supported conclusion | Still unknown |
|---|---|---|
| A symbol appears on a threshold list | The security was listed for that date | The cause and participants behind the fails |
| An uninterrupted listing streak | Membership continued across verified dates | Whether the same failed positions persisted |
| A broker displays HTB | That broker regards it as hard to borrow then | Other brokers’ inventory, prices, and terms |
| A squeeze narrative on social media | Someone has proposed an explanation | Whether evidence supports it |
Separate these observations in your notes. A listed symbol does not tell you the size of all short positions, whether your account can borrow shares, or the next execution price. For the borrow side, read Stock locates: availability, fees, and limits.
Why a listing date is not a 13-day squeeze timer
Rule 203(b)(3) addresses a clearing participant’s fail position in a threshold security persisting for 13 consecutive settlement days and the resulting close-out obligation. The public list does not expose each participant’s position history. The SEC staff FAQ explains the conditions and counting mechanics.
A symbol can remain listed without every day representing the same participant and failed position. Adding 13 days to its first appearance cannot establish a market-wide covering deadline. Rule 204 also imposes delivery-failure close-out requirements; 13 days is not a general grace period for all trades.
The list cannot establish the size, execution time, or price impact of future purchases. Record the streak as research context. A predicted rally date would require evidence the list does not supply.
Read the three dates separately
| Date label | Meaning | How to read it |
|---|---|---|
| As of / list date | The date represented by the displayed list | Establish which day you are looking at |
| Current streak since | The confirmed start of this run in the same source | This run, not necessarily the first-ever listing |
| At least since | The earliest verified date in the continuous history checked so far | An earlier start remains possible |
Suppose a fictional display says “As of 2026-09-23” and a row says “At least since 2026-09-09.” Your note should say that, as of the September 23 list, the verified run extends back at least to September 9. It does not establish a first-ever listing on September 9 or continued membership on September 25.
A practical check in FennEdge
When FennEdge Scanner surfaces a stock, record the observation time and reason for investigating. Then sign in to the FennEdge Reg SHO Threshold List. Read the As of date beneath the list title, then search a ticker or company name, or use the alphabetical directory. Each row pairs its streak date with an official source link so you can trace the observation.
These are dated daily lists, not a feed that changes with every trade. Sources can publish or become available at different times. When a newer complete list is unavailable, the tool retains an available previous complete list and labels its date. That preserves a historical observation; it cannot establish membership for a date that has not been obtained.
Confirming a streak start requires continuous history from the same source and verified absence on the preceding applicable trading day. Where earlier history is incomplete, “At least since” keeps that uncertainty visible.
Use FennEdge Research for company context and disclosures, then preserve list dates, source links, and open questions in ticker notes in FennEdge Desk. When reviewing records in FennEdge Journal, distinguish information available at the time from actual execution. List membership does not automatically explain a trade’s outcome.
Continue with the announcement and timeline research guide to examine the day’s catalyst. Threshold membership adds settlement context; your wider explanation still needs its own evidence. Keep the trading glossary nearby for unfamiliar terms.
Reg SHO threshold-list FAQ
Does inclusion prove illegal naked short selling? No. Long sales and processing issues can also produce fails. Establishing the cause and whether a violation occurred requires evidence beyond the list.
Are FTDs the same as short interest? No. FTDs describe securities not delivered when due; short interest describes outstanding short positions. A properly borrowed and settled short position can remain open. Neither list membership nor trading volume supplies the size of failed positions.
Does removal mean every fail is gone? No. Removal involves consecutive settlement days below the relevant threshold, not proof that all delivery failures have disappeared.
Where can I check membership? Sign in to the FennEdge Reg SHO tool to look up a symbol, then follow its official source and verify the list date. If the date you need is missing, absence from an older list cannot establish absence today.
Sources checked September 25, 2026. Rule references and official lists are linked beside the relevant explanations. Staff FAQs are interpretive guidance and should be read alongside the rules.
This article explains common concepts; examples are not trading recommendations.
