XOOMAR

Sionna Therapeutics, Inc. (SION)

Every FINRA and SEC series the site collects for Sionna Therapeutics, Inc.: short interest with days to cover, daily short sale volume, fails to deliver and Form 4 insider trades. Listed on Nasdaq, classified by the SEC as pharmaceutical preparations.

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4.2M

Short interest

settlement 2026-08-14

1.0

Days to cover

+1.2% vs prior

44.5%

Short share of volume

2026-09-11

13,771

Fails to deliver

settlement 2026-08-14

$0

Insider flow, 90 days

0 buys, 0 sells

As of 2026-09-11.

Short interest

FINRA, twice a month; the last 12 months shown, all 37 settlements in the JSON

As of 14 August 2026, short interest in SION is 4,247,834 shares, down 1,009,443 shares over the last month. Over the last 37 readings it ranged from 630,656 shares (14 February 2025) to 5,522,307 shares (30 June 2026). At the reported average volume of 7.4M shares a day that is 1.0 days to cover.

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SettlementShares shortChangeAvg daily volumeDays to cover
2026-08-144,247,834+1.2%7,351,9351.00
2026-07-314,198,394-20.1%618,0006.79
2026-07-155,257,277-4.8%456,75311.51
2026-06-305,522,307+10.5%544,38710.14
2026-06-154,996,300+7.7%360,22013.87
2026-05-294,639,069-2.1%319,20414.53
2026-05-154,740,815+12.1%421,44911.25
2026-04-304,230,439+11.3%455,3689.29
2026-04-153,799,971+1.1%446,3138.51
2026-03-313,756,705+6.0%332,75911.29
2026-03-133,544,166+5.8%287,31912.34
2026-02-273,350,255+9.3%143,39423.36
2026-02-133,064,857-2.5%407,2207.53
2026-01-303,143,560+2.9%231,94913.55
2026-01-153,053,667-6.3%312,3059.78
2025-12-313,258,091+13.3%384,5348.47
2025-12-152,876,610+0.5%289,3539.94
2025-11-282,862,557-3.7%266,25410.75
2025-11-142,973,430+0.3%194,70015.27
2025-10-312,965,776-12.1%364,6268.13
2025-10-153,372,058-14.2%299,61811.25
2025-09-303,931,123+4.2%330,55211.89
2025-09-153,771,820+8.5%306,32112.31
2025-08-293,475,743-3.5%197,58817.59

Daily short volume

FINRA Reg SHO, last 60 sessions. JSON

As of 11 September 2026, the short share of SION volume is 44.5%, up 13.4 points over the last five sessions. Over the last 52 readings it ranged from 20.2% (11 August 2026) to 71.8% (7 August 2026). The latest reading is in line with the 30-session average of 43.1%, on 486K shares reported.

DateShort volumeTotal volumeShort shareExempt
2026-09-11216K486K44.5%30,039
2026-09-10285K498K57.1%0
2026-09-09127K310K41.0%711
2026-09-08151K394K38.4%0
2026-09-04121K375K32.3%8,244
2026-09-03178K571K31.2%2,660
2026-09-02295K670K44.1%2,022
2026-09-01216K566K38.3%453
2026-08-31134K311K43.1%202
2026-08-2886K238K36.0%0
2026-08-27105K378K27.8%26
2026-08-26153K431K35.6%0
2026-08-25208K857K24.2%3,700
2026-08-24312K885K35.3%1,270
2026-08-21342K851K40.2%50,882
2026-08-20359K708K50.7%25,126
2026-08-19228K627K36.4%1,656
2026-08-18413K1.0M41.3%2,561
2026-08-17560K1.4M39.2%15,383
2026-08-14389K1.2M33.3%8,575
2026-08-13990K2.6M37.5%15,875
2026-08-121.2M5.3M21.6%29,995
2026-08-111.5M7.2M20.2%151,787
2026-08-1011.1M19.2M57.7%1,343,106
2026-08-07255K355K71.8%3,397
2026-08-06202K355K57.0%3
2026-08-05193K288K67.0%0
2026-08-04316K509K62.0%100
2026-08-03158K249K63.5%0
2026-07-31107K161K66.0%0

Fails to deliver

SEC, by settlement date. JSON

As of 14 August 2026, the fails-to-deliver balance in SION is 13,771 shares, up 10,363 shares over the last settlement date. Over the last 52 readings it ranged from 1 share (5 March 2026) to 120,409 shares (29 June 2026).

SettlementShares failedPriceValue
2026-08-1413,771$6.54$90K
2026-08-133,408$6.25$21K
2026-08-12498$5.10$3K
2026-08-112,315$4.50$10K
2026-08-053$49.94$150
2026-08-041$49.26$49
2026-08-0311$47.13$518
2026-07-291,736$46.55$81K
2026-07-16908$44.38$40K
2026-07-0713$43.12$561
2026-07-063,753$43.99$165K
2026-07-027,391$41.64$308K
2026-06-309,681$42.97$416K
2026-06-29120,409$42.18$5.1M
2026-06-251,101$41.09$45K
2026-06-241,886$39.87$75K
2026-06-2390$38.83$3K
2026-06-2266$37.30$2K
2026-06-15353$35.92$13K
2026-06-12186$36.05$7K
2026-06-1024,749$33.69$834K
2026-04-29615$39.59$24K
2026-04-281,307$39.21$51K
2026-04-2730$38.11$1K
2026-04-226$41.79$251
2026-04-20460$43.54$20K
2026-04-17721$45.24$33K
2026-04-166,569$45.09$296K
2026-04-14397$41.77$17K
2026-04-132,168$37.89$82K

Insider trades

SEC Form 4, newest first, 50 of 100 shown. JSON

No open-market insider trades were reported for SION in the last 90 days. The most recent filings are listed below; grants and option exercises carry a weaker signal than voluntary trades. Latest filing: Thompson Peter A. on 2026-05-27.

DateInsiderTitleTypeSharesPriceValueOwned after
2026-05-27Thompson Peter A.n/aSell101$44.49$4K2.7M
2026-05-27ORBIMED ADVISORS LLCn/aSell101$44.49$4K2.7M
2026-05-11Thompson Peter A.n/aSell185K$46.22$8.5M2.7M
2026-05-11ORBIMED ADVISORS LLCn/aSell185K$46.22$8.5M2.7M
2026-05-08Thompson Peter A.n/aSell60K$44.58$2.7M2.9M
2026-05-08ORBIMED ADVISORS LLCn/aSell60K$44.58$2.7M2.9M
2026-05-07Thompson Peter A.n/aSell49K$44.61$2.2M2.9M
2026-05-07ORBIMED ADVISORS LLCn/aSell49K$44.61$2.2M2.9M
2026-04-18Thompson Peter A.n/aSell3K$44.52$131K3.0M
2026-04-18ORBIMED ADVISORS LLCn/aSell3K$44.52$131K3.0M
2026-04-17Thompson Peter A.n/aSell52K$44.68$2.3M3.0M
2026-04-17ORBIMED ADVISORS LLCn/aSell52K$44.68$2.3M3.0M
2026-04-16Thompson Peter A.n/aSell227K$45.34$10.3M3.0M
2026-04-16ORBIMED ADVISORS LLCn/aSell227K$45.34$10.3M3.0M
2026-04-15Thompson Peter A.n/aSell236K$44.64$10.5M3.2M
2026-04-15ORBIMED ADVISORS LLCn/aSell236K$44.64$10.5M3.2M
2026-04-14Thompson Peter A.n/aSell48K$44.51$2.1M3.5M
2026-04-14ORBIMED ADVISORS LLCn/aSell48K$44.51$2.1M3.5M
2026-03-05Fitzpatrick JenniferChief Legal OfficerSell10K$33.86$347K0
2026-03-05Fitzpatrick JenniferChief Legal OfficerOption exercise10K$6.11$63K10K
2026-02-03Thompson Peter A.n/aSell29K$44.58$1.3M3.5M
2026-02-03ORBIMED ADVISORS LLCn/aSell29K$44.58$1.3M3.5M
2026-02-02Thompson Peter A.n/aSell2K$44.57$84K3.6M
2026-02-02ORBIMED ADVISORS LLCn/aSell2K$44.57$84K3.6M
2026-01-22TPG GP A, LLCn/aSell250K$40.00$10.0M6.5M
2025-12-24Thompson Peter A.n/aSell33K$44.55$1.5M3.6M
2025-12-24ORBIMED ADVISORS LLCn/aSell33K$44.55$1.5M3.6M
2025-12-19Thompson Peter A.n/aSell875$44.49$39K3.6M
2025-12-19ORBIMED ADVISORS LLCn/aSell875$44.49$39K3.6M
2025-12-18Thompson Peter A.n/aSell100$44.49$4K3.6M
2025-12-18ORBIMED ADVISORS LLCn/aSell100$44.49$4K3.6M
2025-12-17Thompson Peter A.n/aSell900$44.50$40K3.6M
2025-12-17ORBIMED ADVISORS LLCn/aSell900$44.50$40K3.6M
2025-12-05Fitzpatrick JenniferChief Legal OfficerSell10K$40.52$415K0
2025-12-05Fitzpatrick JenniferChief Legal OfficerOption exercise10K$6.11$63K10K
2025-11-26Thompson Peter A.n/aSell2K$44.49$71K3.6M
2025-11-26ORBIMED ADVISORS LLCn/aSell2K$44.49$71K3.6M
2025-11-25Thompson Peter A.n/aSell12K$44.60$530K3.6M
2025-11-25ORBIMED ADVISORS LLCn/aSell12K$44.60$530K3.6M
2025-11-24Thompson Peter A.n/aSell95K$44.54$4.2M3.6M
2025-11-24ORBIMED ADVISORS LLCn/aSell95K$44.54$4.2M3.6M
2025-11-21RA CAPITAL MANAGEMENT, L.P.n/aSell8K$39.50$301K159K
2025-11-21RA CAPITAL MANAGEMENT, L.P.n/aSell6K$39.50$254K2.2M
2025-11-21RA CAPITAL MANAGEMENT, L.P.n/aSell10K$39.50$392K650K
2025-11-21RA CAPITAL MANAGEMENT, L.P.n/aSell1K$39.50$48K6.9M
2025-11-20RA CAPITAL MANAGEMENT, L.P.n/aSell604$40.50$24K167K
2025-11-20RA CAPITAL MANAGEMENT, L.P.n/aSell512$40.50$21K2.2M
2025-11-20RA CAPITAL MANAGEMENT, L.P.n/aSell788$40.50$32K660K
2025-11-20RA CAPITAL MANAGEMENT, L.P.n/aSell96$40.50$4K6.9M
2025-11-20RA CAPITAL MANAGEMENT, L.P.n/aSell947$39.89$38K167K

Form 4 filings are due within two business days of the trade. Insiders sell for many reasons that say nothing about the company; open-market buys are the rarer, stronger signal.

13F holders

Tracked managers holding SION at their latest 13F. JSON

5 of the 30 tracked managers held SION at their latest 13F, $212.4M in total at quarter-end prices. Viking Global Investors is the largest at $140.6M (0.4% of its portfolio) as of 2026-06-30. Over the prior quarter 2 added shares and 2 cut.

FundQuarterSharesValueOf portfolioChange in shares
Viking Global Investors2026-06-303.2M$140.6M0.40%0
Citadel Advisors2026-06-301.2M$50.9M0.01%-11K
Millennium Management2026-06-30325K$14.3M0.01%+185K
D. E. Shaw & Co.2026-06-30102K$4.5M0.00%+96K
Point72 Asset Management2026-06-3049K$2.2M0.00%-87K

Only the 30 tracked managers on the funds hub; a 13F reports long positions in US listed stock at quarter end, 45 days late, and says nothing about shorts or positions sold since.

What this page is

Sionna Therapeutics, Inc. in the regulatory record

Regulators publish company data in separate files that never sit next to each other: FINRA's twice-monthly short interest, its daily short sale volume, the SEC's fails-to-deliver counts, and each insider's Form 4. A company page pulls every series the site collects for one ticker onto one URL, keyed by the SEC's own ticker list, so the short position, the daily flow, the settlement fails and what insiders are doing can be read together.

Each section has its own history table, a summary sentence built from the rows (last value, change, range with dates) and its own JSON and CSV links. Nothing on the page is written by a model; the sentences change only when the data does. A page exists only for companies with data in at least two series, and every section says when its source last updated.

This page follows Sionna Therapeutics, Inc. (SION), SEC CIK 2036042, listed on Nasdaq, classified by the SEC as pharmaceutical preparations. The cross-market tables live on the short interest and insider transactions hubs.

Source and method

Short interest
FINRA consolidated short interestTwice a month, about eight business days after settlement. Latest 2026-08-14.JSON and CSV
Daily short volume
FINRA Reg SHO daily filesEvery trading day, loaded the following morning. Latest 2026-09-11.JSON and CSV
Fails to deliver
SEC fails-to-deliver dataTwice a month, a few weeks after the half month ends. Latest 2026-08-14.JSON and CSV
13F holders
SEC EDGAR Form 13F-HRQuarterly, filed within 45 days of quarter end; 30 tracked managers. Latest 2026-06-30.JSON and CSV
Insider trades
SEC EDGAR Form 4EDGAR read every 30 minutes; filings are due two business days after the trade. Latest 2026-05-27.JSON and CSV
Company record
EDGAR filing index for CIK 2036042Ticker, name and exchange from the SEC's company list, refreshed weekly.
Rate limits
30 requests a minute without a key, 120 a minute with a key from a free account.

Data checks. Every dataset is checked against its source once a day. This dataset passed the last run, 13 Sep 05:40 UTC.

How to read it

  • Read the position against the flow: rising short interest with a high daily short share is new shorting; rising short interest with a normal short share is old shorts holding on.
  • Insider buys next to a crowded short are the combination that has historically preceded squeezes; insider sells next to a crowded short are common and mean little.
  • Fails to deliver matter relative to the float, not in absolute shares; a million failed shares in a mega cap is noise.

Analysis of what the data shows, not advice. XOOMAR does not recommend buying, selling or holding anything.

Other companies the SEC classifies as pharmaceutical preparations

Datasets

Frequently Asked Questions

How much of SION is sold short?
4,247,834 shares were held short at the 2026-08-14 settlement, 1.0 days of average volume. FINRA publishes the next count about eight business days after the 15th and the last business day of the month.
What is SION's daily short volume?
On 2026-09-11, 216,298 of the 485,629 SION shares reported to FINRA were sold short, 44.5% of the day's reported volume. Short volume is a flow for one day, not a position.
Does SION have fails to deliver?
The SEC's latest file shows 13,771 SION shares failed to deliver at settlement 2026-08-14. Fails are reported per settlement date and published twice a month with a lag.
Are SION insiders buying or selling?
No open-market insider trades were reported for SION in the last 90 days. The most recent filings are listed below; grants and option exercises carry a weaker signal than voluntary trades. Latest filing: Thompson Peter A. on 2026-05-27.
Which funds hold SION?
5 of the 30 tracked managers held SION at their latest 13F, $212.4M in total at quarter-end prices. Viking Global Investors is the largest at $140.6M (0.4% of its portfolio) as of 2026-06-30. Over the prior quarter 2 added shares and 2 cut.

Data on this page is provided for informational purposes only and is not financial advice. See our editorial policy.