Sionna Therapeutics (SION)
Sionna Therapeutics on one page: short interest, daily short volume, fails to deliver, planned sales, large holders, 13F holders, earnings dates and insider trades. Listed on Nasdaq, classified by the SEC as pharmaceutical preparations.
3.7M
Short interest
settlement 2026-10-15
3.7
Days to cover
+1.4 days vs prior
42.9%
Short share of volume
2026-11-03
2,445
Fails to deliver
settlement 2026-10-05
Wed 4 Nov
Next earnings
estimated date
-$21.8M
Insider flow, 90 days
0 buys, 2 sells
As of 2026-11-03.
Short interest
FINRA, twice a month. The newest 41 settlements in the table, 41 in the chart. JSONAs of 15 October 2026, short interest in SION is 3,676,508 shares, down 289,630 shares over the last month. Over the last 41 readings it ranged from 630,656 shares (14 February 2025) to 5,522,307 shares (30 June 2026). At the reported average volume of 983K shares a day that is 3.7 days to cover.
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| Settlement | Shares short | Change | Avg daily volume | Days to cover |
|---|---|---|---|---|
| 2026-10-15 | 3,676,508 | -3.2% | 983,094 | 3.74 |
| 2026-09-30 | 3,797,732 | -4.3% | 1,647,766 | 2.30 |
| 2026-09-15 | 3,966,138 | -7.7% | 1,280,298 | 3.10 |
| 2026-08-31 | 4,298,665 | +1.2% | 1,642,953 | 2.62 |
| 2026-08-14 | 4,247,834 | +1.2% | 7,351,935 | 1.00 |
| 2026-07-31 | 4,198,394 | -20.1% | 618,000 | 6.79 |
| 2026-07-15 | 5,257,277 | -4.8% | 456,753 | 11.51 |
| 2026-06-30 | 5,522,307 | +10.5% | 544,387 | 10.14 |
| 2026-06-15 | 4,996,300 | +7.7% | 360,220 | 13.87 |
| 2026-05-29 | 4,639,069 | -2.1% | 319,204 | 14.53 |
| 2026-05-15 | 4,740,815 | +12.1% | 421,449 | 11.25 |
| 2026-04-30 | 4,230,439 | +11.3% | 455,368 | 9.29 |
| 2026-04-15 | 3,799,971 | +1.1% | 446,313 | 8.51 |
| 2026-03-31 | 3,756,705 | +6.0% | 332,759 | 11.29 |
| 2026-03-13 | 3,544,166 | +5.8% | 287,319 | 12.34 |
| 2026-02-27 | 3,350,255 | +9.3% | 143,394 | 23.36 |
| 2026-02-13 | 3,064,857 | -2.5% | 407,220 | 7.53 |
| 2026-01-30 | 3,143,560 | +2.9% | 231,949 | 13.55 |
| 2026-01-15 | 3,053,667 | -6.3% | 312,305 | 9.78 |
| 2025-12-31 | 3,258,091 | +13.3% | 384,534 | 8.47 |
| 2025-12-15 | 2,876,610 | +0.5% | 289,353 | 9.94 |
| 2025-11-28 | 2,862,557 | -3.7% | 266,254 | 10.75 |
| 2025-11-14 | 2,973,430 | +0.3% | 194,700 | 15.27 |
| 2025-10-31 | 2,965,776 | -12.1% | 364,626 | 8.13 |
| 2025-10-15 | 3,372,058 | -14.2% | 299,618 | 11.25 |
| 2025-09-30 | 3,931,123 | +4.2% | 330,552 | 11.89 |
| 2025-09-15 | 3,771,820 | +8.5% | 306,321 | 12.31 |
| 2025-08-29 | 3,475,743 | -3.5% | 197,588 | 17.59 |
| 2025-08-15 | 3,600,368 | -2.1% | 174,663 | 20.61 |
| 2025-07-31 | 3,679,050 | +4.2% | 144,879 | 25.39 |
| 2025-07-15 | 3,530,059 | -2.8% | 159,485 | 22.13 |
| 2025-06-30 | 3,631,953 | +28.5% | 355,385 | 10.22 |
| 2025-06-13 | 2,827,394 | -1.6% | 138,557 | 20.41 |
| 2025-05-30 | 2,871,885 | +11.0% | 117,759 | 24.39 |
| 2025-05-15 | 2,587,312 | +3.4% | 173,929 | 14.88 |
| 2025-04-30 | 2,502,341 | +9.2% | 108,120 | 23.14 |
| 2025-04-15 | 2,291,588 | +0.5% | 180,542 | 12.69 |
| 2025-03-31 | 2,280,720 | +31.1% | 272,157 | 8.38 |
| 2025-03-14 | 1,739,754 | +30.9% | 201,340 | 8.64 |
| 2025-02-28 | 1,329,000 | +110.7% | 199,950 | 6.65 |
| 2025-02-14 | 630,656 | +100.0% | 301,375 | 2.09 |
Daily short volume
FINRA Reg SHO, the last 30 sessions. JSONAs of 3 November 2026, the short share of SION volume is 42.9%, up 10.7 points over the last five sessions. Over the last 30 readings it ranged from 31.4% (5 October 2026) to 66.4% (16 October 2026). The latest reading is 3.6 points below the 30-session average of 46.4%, on 360K shares reported.
| Date | Short volume | Total volume | Short share | Exempt |
|---|---|---|---|---|
| 2026-11-03 | 155K | 360K | 42.9% | 0 |
| 2026-11-02 | 142K | 295K | 48.0% | 25 |
| 2026-10-30 | 71K | 163K | 43.6% | 0 |
| 2026-10-29 | 88K | 271K | 32.5% | 0 |
| 2026-10-28 | 117K | 283K | 41.4% | 0 |
| 2026-10-27 | 146K | 453K | 32.2% | 5 |
| 2026-10-26 | 155K | 287K | 54.0% | 0 |
| 2026-10-23 | 247K | 433K | 57.0% | 100 |
| 2026-10-22 | 288K | 547K | 52.6% | 0 |
| 2026-10-21 | 306K | 522K | 58.7% | 300 |
| 2026-10-20 | 143K | 420K | 34.0% | 1 |
| 2026-10-19 | 311K | 519K | 60.0% | 0 |
| 2026-10-16 | 410K | 618K | 66.4% | 20 |
| 2026-10-15 | 186K | 374K | 49.6% | 4,833 |
| 2026-10-14 | 380K | 728K | 52.2% | 3,665 |
| 2026-10-13 | 164K | 331K | 49.4% | 263 |
| 2026-10-12 | 112K | 272K | 41.1% | 5 |
| 2026-10-09 | 83K | 185K | 45.0% | 0 |
| 2026-10-08 | 72K | 201K | 35.8% | 0 |
| 2026-10-07 | 177K | 342K | 51.8% | 121 |
| 2026-10-06 | 284K | 651K | 43.7% | 0 |
| 2026-10-05 | 178K | 567K | 31.4% | 0 |
| 2026-10-02 | 207K | 475K | 43.6% | 340 |
| 2026-10-01 | 267K | 406K | 65.8% | 0 |
| 2026-09-30 | 238K | 408K | 58.4% | 0 |
| 2026-09-29 | 119K | 334K | 35.7% | 0 |
| 2026-09-28 | 140K | 340K | 41.1% | 431 |
| 2026-09-25 | 197K | 504K | 39.2% | 0 |
| 2026-09-24 | 296K | 650K | 45.6% | 12,870 |
| 2026-09-23 | 322K | 801K | 40.3% | 11,095 |
Fails to deliver
SEC, the last 30 settlement dates with a fail. JSONAs of 5 October 2026, the fails-to-deliver balance in SION is 2,445 shares, up 2,174 shares over the last settlement date. Over the last 30 readings it ranged from 1 share (4 August 2026) to 99,175 shares (26 August 2026). The latest reading sits at the bottom of that range.
| Settlement | Shares failed | Price | Value |
|---|---|---|---|
| 2026-10-05 | 2,445 | $4.91 | $12K |
| 2026-10-01 | 271 | $5.26 | $1K |
| 2026-09-23 | 1,703 | $6.02 | $10K |
| 2026-09-16 | 1,765 | $6.88 | $12K |
| 2026-09-15 | 338 | $8.26 | $3K |
| 2026-09-11 | 39,094 | $7.62 | $298K |
| 2026-09-09 | 18,174 | $7.30 | $133K |
| 2026-09-08 | 61,912 | $7.18 | $445K |
| 2026-09-03 | 6,233 | $7.31 | $46K |
| 2026-09-02 | 4,120 | $6.46 | $27K |
| 2026-09-01 | 69,585 | $6.03 | $420K |
| 2026-08-31 | 40,891 | $5.87 | $240K |
| 2026-08-26 | 99,175 | $6.25 | $620K |
| 2026-08-25 | 85,182 | $5.59 | $476K |
| 2026-08-24 | 90,445 | $5.29 | $478K |
| 2026-08-21 | 89,243 | $5.52 | $493K |
| 2026-08-20 | 8,179 | $6.25 | $51K |
| 2026-08-19 | 700 | $5.94 | $4K |
| 2026-08-17 | 6,780 | $6.46 | $44K |
| 2026-08-14 | 13,771 | $6.54 | $90K |
| 2026-08-13 | 3,408 | $6.25 | $21K |
| 2026-08-12 | 498 | $5.10 | $3K |
| 2026-08-11 | 2,315 | $4.50 | $10K |
| 2026-08-05 | 3 | $49.94 | $150 |
| 2026-08-04 | 1 | $49.26 | $49 |
| 2026-08-03 | 11 | $47.13 | $518 |
| 2026-07-29 | 1,736 | $46.55 | $81K |
| 2026-07-16 | 908 | $44.38 | $40K |
| 2026-07-07 | 13 | $43.12 | $561 |
| 2026-07-06 | 3,753 | $43.99 | $165K |
Insider trades
SEC Form 4, newest first. JSONInsiders at SION reported 2 open-market sells worth $21.8M in the last 90 days and no open-market buys. Latest filing: McKee Charlotte (CMO and Head of R&D) on 2026-09-17.
| Date | Insider | Title | Type | Shares | Price | Value | Owned after |
|---|---|---|---|---|---|---|---|
| 2026-09-17 | McKee Charlotte | CMO and Head of R&D | Grant | 50K | $0.00 | $0 | 128K |
| 2026-09-17 | Cloonan Michael | President & CEO | Grant | 109K | $0.00 | $0 | 765K |
| 2026-09-17 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 34K | $7.46 | $252K | 3.4M |
| 2026-09-17 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 3.4M | $6.32 | $21.6M | 3.5M |
| 2026-09-17 | Cloonan Michael | President & CEO | Grant | 109K | $0.00 | $0 | 656K |
| 2026-09-17 | Fitzpatrick Jennifer | CLO and Head of Program Mgmt. | Grant | 28K | $0.00 | $0 | 56K |
| 2026-09-17 | Fitzpatrick Jennifer | CLO and Head of Program Mgmt. | Grant | 28K | $0.00 | $0 | 28K |
| 2026-09-17 | McKee Charlotte | CMO and Head of R&D | Grant | 50K | $0.00 | $0 | 78K |
| 2026-09-17 | Ridloff Elena | CFO and CBO | Grant | 47K | $0.00 | $0 | 133K |
| 2026-09-17 | Ridloff Elena | CFO and CBO | Grant | 47K | $0.00 | $0 | 86K |
| 2026-07-07 | Thompson Peter A. | Director | Sell | 86K | $44.86 | $3.9M | 2.5M |
| 2026-07-07 | ORBIMED ADVISORS LLC | Director | Sell | 86K | $44.86 | $3.9M | 2.5M |
| 2026-07-06 | Fitzpatrick Jennifer | Chief Legal Officer | Sell | 10K | $43.60 | $447K | 0 |
| 2026-07-06 | Fitzpatrick Jennifer | Chief Legal Officer | Exercise or conversion | 10K | $6.11 | $63K | 10K |
| 2026-06-30 | Thompson Peter A. | Director | Sell | 116K | $45.50 | $5.3M | 2.6M |
| 2026-06-30 | ORBIMED ADVISORS LLC | Director | Sell | 116K | $45.50 | $5.3M | 2.6M |
| 2026-05-27 | Thompson Peter A. | Director | Sell | 101 | $44.49 | $4K | 2.7M |
| 2026-05-27 | ORBIMED ADVISORS LLC | Director | Sell | 101 | $44.49 | $4K | 2.7M |
| 2026-05-11 | Thompson Peter A. | Director | Sell | 185K | $46.22 | $8.5M | 2.7M |
| 2026-05-11 | ORBIMED ADVISORS LLC | Director | Sell | 185K | $46.22 | $8.5M | 2.7M |
| 2026-05-08 | Thompson Peter A. | Director | Sell | 60K | $44.58 | $2.7M | 2.9M |
| 2026-05-08 | ORBIMED ADVISORS LLC | Director | Sell | 60K | $44.58 | $2.7M | 2.9M |
| 2026-05-07 | Thompson Peter A. | Director | Sell | 49K | $44.61 | $2.2M | 2.9M |
| 2026-05-07 | ORBIMED ADVISORS LLC | Director | Sell | 49K | $44.61 | $2.2M | 2.9M |
| 2026-04-18 | Thompson Peter A. | Director | Sell | 3K | $44.52 | $131K | 3.0M |
| 2026-04-18 | ORBIMED ADVISORS LLC | Director | Sell | 3K | $44.52 | $131K | 3.0M |
| 2026-04-17 | Thompson Peter A. | Director | Sell | 52K | $44.68 | $2.3M | 3.0M |
| 2026-04-17 | ORBIMED ADVISORS LLC | Director | Sell | 52K | $44.68 | $2.3M | 3.0M |
| 2026-04-16 | Thompson Peter A. | Director | Sell | 227K | $45.34 | $10.3M | 3.0M |
| 2026-04-16 | ORBIMED ADVISORS LLC | Director | Sell | 227K | $45.34 | $10.3M | 3.0M |
| 2026-04-15 | Thompson Peter A. | Director | Sell | 236K | $44.64 | $10.5M | 3.2M |
| 2026-04-15 | ORBIMED ADVISORS LLC | Director | Sell | 236K | $44.64 | $10.5M | 3.2M |
| 2026-04-14 | Thompson Peter A. | Director | Sell | 48K | $44.51 | $2.1M | 3.5M |
| 2026-04-14 | ORBIMED ADVISORS LLC | Director | Sell | 48K | $44.51 | $2.1M | 3.5M |
| 2026-03-05 | Fitzpatrick Jennifer | Chief Legal Officer | Sell | 10K | $33.86 | $347K | 0 |
| 2026-03-05 | Fitzpatrick Jennifer | Chief Legal Officer | Exercise or conversion | 10K | $6.11 | $63K | 10K |
| 2026-02-03 | OrbiMed Capital GP VIII LLC | Director | Sell | 29K | $44.58 | $1.3M | 3.5M |
| 2026-02-03 | Thompson Peter A. | Director | Sell | 29K | $44.58 | $1.3M | 3.5M |
| 2026-02-03 | ORBIMED ADVISORS LLC | Director | Sell | 29K | $44.58 | $1.3M | 3.5M |
| 2026-02-02 | OrbiMed Capital GP VIII LLC | Director | Sell | 2K | $44.57 | $84K | 3.6M |
| 2026-02-02 | Thompson Peter A. | Director | Sell | 2K | $44.57 | $84K | 3.6M |
| 2026-02-02 | ORBIMED ADVISORS LLC | Director | Sell | 2K | $44.57 | $84K | 3.6M |
| 2026-01-22 | WINKELRIED JON | TenPercentOwner | Sell | 250K | $40.00 | $10.0M | 6.5M |
| 2026-01-22 | TPG GP A, LLC | 10% owner | Sell | 250K | $40.00 | $10.0M | 6.5M |
| 2025-12-24 | OrbiMed Capital GP VIII LLC | Director | Sell | 33K | $44.55 | $1.5M | 3.6M |
| 2025-12-24 | Thompson Peter A. | Director | Sell | 33K | $44.55 | $1.5M | 3.6M |
| 2025-12-24 | ORBIMED ADVISORS LLC | Director | Sell | 33K | $44.55 | $1.5M | 3.6M |
| 2025-12-19 | OrbiMed Capital GP VIII LLC | Director | Sell | 875 | $44.49 | $39K | 3.6M |
| 2025-12-19 | Thompson Peter A. | Director | Sell | 875 | $44.49 | $39K | 3.6M |
| 2025-12-19 | ORBIMED ADVISORS LLC | Director | Sell | 875 | $44.49 | $39K | 3.6M |
| 2025-12-18 | OrbiMed Capital GP VIII LLC | Director | Sell | 100 | $44.49 | $4K | 3.6M |
| 2025-12-18 | Thompson Peter A. | Director | Sell | 100 | $44.49 | $4K | 3.6M |
| 2025-12-18 | ORBIMED ADVISORS LLC | Director | Sell | 100 | $44.49 | $4K | 3.6M |
| 2025-12-17 | OrbiMed Capital GP VIII LLC | Director | Sell | 900 | $44.50 | $40K | 3.6M |
| 2025-12-17 | Thompson Peter A. | Director | Sell | 900 | $44.50 | $40K | 3.6M |
| 2025-12-17 | ORBIMED ADVISORS LLC | Director | Sell | 900 | $44.50 | $40K | 3.6M |
| 2025-12-05 | Fitzpatrick Jennifer | Chief Legal Officer | Sell | 10K | $40.52 | $415K | 0 |
| 2025-12-05 | Fitzpatrick Jennifer | Chief Legal Officer | Exercise or conversion | 10K | $6.11 | $63K | 10K |
| 2025-11-26 | Thompson Peter A. | Director | Sell | 2K | $44.49 | $71K | 3.6M |
| 2025-11-26 | ORBIMED ADVISORS LLC | Director | Sell | 2K | $44.49 | $71K | 3.6M |
| 2025-11-25 | Thompson Peter A. | Director | Sell | 12K | $44.60 | $530K | 3.6M |
| 2025-11-25 | ORBIMED ADVISORS LLC | Director | Sell | 12K | $44.60 | $530K | 3.6M |
| 2025-11-24 | Thompson Peter A. | Director | Sell | 95K | $44.54 | $4.2M | 3.6M |
| 2025-11-24 | ORBIMED ADVISORS LLC | Director | Sell | 95K | $44.54 | $4.2M | 3.6M |
| 2025-11-21 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 6K | $39.50 | $254K | 2.2M |
| 2025-11-21 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 10K | $39.50 | $392K | 650K |
| 2025-11-21 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 1K | $39.50 | $48K | 6.9M |
| 2025-11-21 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 8K | $39.50 | $301K | 159K |
| 2025-11-21 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 8K | $39.50 | $301K | 159K |
| 2025-11-21 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 6K | $39.50 | $254K | 2.2M |
| 2025-11-21 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 10K | $39.50 | $392K | 650K |
| 2025-11-21 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 1K | $39.50 | $48K | 6.9M |
| 2025-11-20 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 788 | $40.50 | $32K | 660K |
| 2025-11-20 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 604 | $40.50 | $24K | 167K |
| 2025-11-20 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 512 | $40.50 | $21K | 2.2M |
| 2025-11-20 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 96 | $40.50 | $4K | 6.9M |
| 2025-11-20 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 947 | $39.89 | $38K | 167K |
| 2025-11-20 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 801 | $39.89 | $32K | 2.2M |
| 2025-11-20 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 1K | $39.89 | $49K | 661K |
| 2025-11-20 | Kolchinsky Peter | Director,TenPercentOwner | Sell | 150 | $39.89 | $6K | 6.9M |
| 2025-11-20 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 604 | $40.50 | $24K | 167K |
| 2025-11-20 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 512 | $40.50 | $21K | 2.2M |
| 2025-11-20 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 788 | $40.50 | $32K | 660K |
| 2025-11-20 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 96 | $40.50 | $4K | 6.9M |
| 2025-11-20 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 947 | $39.89 | $38K | 167K |
| 2025-11-20 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 801 | $39.89 | $32K | 2.2M |
| 2025-11-20 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 1K | $39.89 | $49K | 661K |
| 2025-11-20 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 150 | $39.89 | $6K | 6.9M |
| 2025-11-19 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 9 | $40.61 | $365 | 168K |
| 2025-11-19 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 8 | $40.61 | $325 | 2.2M |
| 2025-11-19 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 12 | $40.61 | $487 | 662K |
| 2025-11-19 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 2 | $40.61 | $81 | 6.9M |
| 2025-11-19 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 14K | $40.01 | $573K | 168K |
| 2025-11-19 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 12K | $40.01 | $485K | 2.2M |
| 2025-11-19 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 19K | $40.01 | $748K | 662K |
| 2025-11-19 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 2K | $40.01 | $91K | 6.9M |
| 2025-11-18 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 2K | $39.57 | $83K | 183K |
| 2025-11-18 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 2K | $39.57 | $70K | 2.2M |
| 2025-11-18 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 3K | $39.57 | $108K | 681K |
| 2025-11-18 | RA CAPITAL MANAGEMENT, L.P. | Director, 10% owner | Sell | 332 | $39.57 | $13K | 6.9M |
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 rarer.
Planned sales (Form 144)
Newest first. JSON50 Form 144 notices on file for SION worth $174.3M at the prices reported; 1 in the last 90 days worth $21.8M. Latest: RA Capital Healthcare Fund, L.P. filed on 2026-09-17 to sell 3,448,811 shares ($21.8M) from 2026-09-17.
| Filed | Seller | Shares | Market value | Of outstanding | Sale from | Broker |
|---|---|---|---|---|---|---|
| 2026-09-17 | RA Capital Healthcare Fund, L.P.Director, 10% Stockholder | 3.4M | $21.8M | 7.628% | 2026-09-17 | Goldman Sachs & Co |
| 2026-07-06 | JENNIFER FITZPATRICKOfficer | 10K | $451K | 0.023% | 2026-07-06 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-06-01 | OrbiMed Private Investments VIII, LPShareholder | 211K | $9.0M | 0.467% | 2026-05-29 | TD Cowen |
| 2026-05-29 | OrbiMed Private Investments VIII, LPShareholder | 1.1M | $46.3M | 2.398% | 2026-05-29 | TD Cowen |
| 2026-03-05 | JENNIFER FITZPATRICKOfficer | 10K | $354K | 0.023% | 2026-03-05 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-01-22 | Rise Fund Sling, L.P.Stockholder | 196K | $8.2M | 0.438% | 2026-01-22 | Goldman Sachs & Co. LLC |
| 2026-01-22 | Rise Fund Sling II, L.P.Stockholder | 54K | $2.3M | 0.122% | 2026-01-22 | Goldman Sachs & Co. LLC |
| 2025-12-05 | JENNIFER R FITZPATRICKOfficer | 10K | $419K | 0.023% | 2025-12-05 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2025-11-24 | OrbiMed Private Investments VIII, LPShareholder | 1.0M | $46.5M | 2.348% | 2025-11-24 | TD Cowen |
| 2025-11-21 | RA Capital Nexus Fund, L.P.Director, 10% Stockholder | 10K | $433K | 0.022% | 2025-11-21 | BTIG, LLC |
| 2025-11-21 | RA Capital Nexus Fund III, L.P.Director, 10% Stockholder | 6K | $281K | 0.014% | 2025-11-21 | BTIG, LLC |
| 2025-11-21 | RA Capital Healthcare Fund LPDirector, 10% Stockholder | 1K | $53K | 0.003% | 2025-11-21 | BTIG, LLC |
| 2025-11-21 | BLACKWELL PARTNERS LLC - SERIES ADirector, 10% Stockholder | 8K | $332K | 0.017% | 2025-11-21 | BTIG, LLC |
| 2025-11-20 | RA Capital Nexus Fund, L.P.Director, 10% Stockholder | 2K | $79K | 0.005% | 2025-11-20 | BTIG, LLC |
| 2025-11-20 | RA Capital Nexus Fund III, L.P.Director, 10% Stockholder | 1K | $51K | 0.003% | 2025-11-20 | BTIG, LLC |
| 2025-11-20 | RA Capital Healthcare Fund LPDirector, 10% Stockholder | 246 | $10K | 0.001% | 2025-11-20 | BTIG, LLC |
| 2025-11-20 | BLACKWELL PARTNERS LLC - SERIES ADirector, 10% Stockholder | 2K | $60K | 0.003% | 2025-11-20 | BTIG, LLC |
| 2025-11-19 | RA Capital Nexus Fund, L.P.Director, 10% Stockholder | 19K | $718K | 0.042% | 2025-11-19 | BTIG, LLC |
| 2025-11-19 | RA Capital Nexus Fund III, L.P.Director, 10% Stockholder | 12K | $466K | 0.027% | 2025-11-19 | BTIG, LLC |
| 2025-11-19 | RA Capital Healthcare Fund LPDirector, 10% Stockholder | 2K | $89K | 0.005% | 2025-11-19 | BTIG, LLC |
| 2025-11-19 | BLACKWELL PARTNERS LLC - SERIES ADirector, 10% Stockholder | 14K | $551K | 0.032% | 2025-11-19 | BTIG, LLC |
| 2025-11-18 | RA Capital Nexus Fund, L.P.Director, 10% Stockholder | 3K | $107K | 0.006% | 2025-11-18 | BTIG, LLC |
| 2025-11-18 | RA Capital Nexus Fund III, L.P.Director, 10% Stockholder | 2K | $69K | 0.004% | 2025-11-18 | BTIG, LLC |
| 2025-11-18 | RA Capital Healthcare Fund LPDirector, 10% Stockholder | 332 | $13K | 0.001% | 2025-11-18 | BTIG, LLC |
| 2025-11-18 | BLACKWELL PARTNERS LLC - SERIES ADirector, 10% Stockholder | 2K | $82K | 0.005% | 2025-11-18 | BTIG, LLC |
| 2025-11-17 | RA Capital Nexus Fund, L.P.Director, 10% Stockholder | 32K | $1.3M | 0.072% | 2025-11-17 | BTIG, LLC |
| 2025-11-17 | RA Capital Nexus Fund III, L.P.Director, 10% Stockholder | 21K | $837K | 0.047% | 2025-11-17 | BTIG, LLC |
| 2025-11-17 | RA Capital Healthcare Fund LPDirector, 10% Stockholder | 4K | $157K | 0.009% | 2025-11-17 | BTIG, LLC |
| 2025-11-17 | BLACKWELL PARTNERS LLC - SERIES ADirector, 10% Stockholder | 25K | $989K | 0.056% | 2025-11-17 | BTIG, LLC |
| 2025-10-28 | RA Capital Nexus Fund, L.P.Director, 10% Stockholder | 31K | $1.2M | 0.071% | 2025-10-28 | BTIG, LLC |
| 2025-10-28 | RA Capital Nexus Fund III, L.P.Director, 10% Stockholder | 17K | $675K | 0.039% | 2025-10-28 | BTIG, LLC |
| 2025-10-28 | RA Capital Healthcare Fund LPDirector, 10% Stockholder | 4K | $143K | 0.008% | 2025-10-28 | BTIG, LLC |
| 2025-10-28 | BLACKWELL PARTNERS LLC - SERIES ADirector, 10% Stockholder | 10K | $413K | 0.024% | 2025-10-28 | BTIG, LLC |
| 2025-10-24 | RA Capital Nexus Fund, L.P.Director, 10% Stockholder | 122K | $4.8M | 0.277% | 2025-10-24 | BTIG, LLC |
| 2025-10-24 | RA Capital Nexus Fund III, L.P.Director, 10% Stockholder | 67K | $2.6M | 0.151% | 2025-10-24 | BTIG, LLC |
| 2025-10-24 | RA Capital Healthcare Fund LPDirector, 10% Stockholder | 14K | $553K | 0.032% | 2025-10-24 | BTIG, LLC |
| 2025-10-24 | BLACKWELL PARTNERS LLC - SERIES ADirector, 10% Stockholder | 108K | $4.2M | 0.245% | 2025-10-24 | BTIG, LLC |
| 2025-10-21 | MICHAEL CLOONANDirector, Officer | 100K | $3.2M | 0.226% | 2025-10-21 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2025-10-21 | Atlas Venture Opportunity Fund II, L.P.Shareholder | 15K | $496K | 0.035% | 2025-10-21 | Merrill Lynch |
| 2025-10-21 | Atlas Venture Fund XI, LPShareholder | 73K | $2.4M | 0.166% | 2025-10-21 | Merrill Lynch |
| 2025-10-20 | Atlas Venture Opportunity Fund II, L.P.Shareholder | 10K | $310K | 0.022% | 2025-10-20 | Merrill Lynch |
| 2025-10-20 | Atlas Venture Fund XI, LPShareholder | 46K | $1.5M | 0.105% | 2025-10-20 | Merrill Lynch |
| 2025-10-17 | Atlas Venture Opportunity Fund II, L.P.Shareholder | 11K | $347K | 0.024% | 2025-10-17 | Merrill Lynch |
| 2025-10-17 | Atlas Venture Fund XI, LPShareholder | 51K | $1.7M | 0.114% | 2025-10-17 | Merrill Lynch |
| 2025-10-16 | MICHAEL CLOONANDirector, Officer | 200 | $6K | 0.000% | 2025-10-16 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2025-10-16 | Atlas Venture Opportunity Fund II, L.P.Shareholder | 29K | $908K | 0.067% | 2025-10-16 | Merrill Lynch |
| 2025-10-16 | Atlas Venture Fund XI, LPShareholder | 140K | $4.3M | 0.317% | 2025-10-16 | Merrill Lynch |
| 2025-10-15 | MICHAEL CLOONANDirector, Officer | 25K | $749K | 0.057% | 2025-10-15 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2025-10-14 | Atlas Venture Opportunity Fund II, L.P.Shareholder | 10K | $297K | 0.023% | 2025-10-13 | Merrill Lynch |
| 2025-10-14 | Atlas Venture Fund XI, LPShareholder | 48K | $1.4M | 0.109% | 2025-10-13 | Merrill Lynch |
Large holders (13D and 13G)
One row per reporting person with its latest filing, newest first. JSON13 holders report 5% or more of SION in their latest filing, 9 on Schedule 13D (active intent). The largest reported stake is Rajeev Shah at 14.3% of the class (6,476,193 shares), filed 2026-09-21 for an event on 2026-09-17.
| Filed | Form | Holder | Shares | Of class | Event |
|---|---|---|---|---|---|
| 2026-09-21 | 13D/Ano. 2 | Rajeev Shahparent holding company, individual | 6.5M | 14.3% | 2026-09-17 |
| 2026-09-21 | 13D/Ano. 2 | Peter Kolchinskyparent holding company, individual | 6.5M | 14.3% | 2026-09-17 |
| 2026-09-21 | 13D/Ano. 2 | RA Capital Management, L.P.investment adviser, partnership | 6.5M | 14.3% | 2026-09-17 |
| 2026-09-21 | 13D/Ano. 2 | RA Capital Healthcare Fund, L.P.partnership | 3.4M | 7.6% | 2026-09-17 |
| 2026-09-21 | 13D/Ano. 2 | RA Capital Nexus Fund III, L.P.partnership | 2.2M | 4.9% | 2026-09-17 |
| 2026-05-15 | 13G/Ano. 1 | VIKING GLOBAL INVESTORS LPpartnership | 3.2M | 7.1% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | Shabet Rose Sharonindividual | 3.2M | 7.1% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | HALVORSEN OLE ANDREASindividual | 3.2M | 7.1% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | Viking Global Opportunities Parent GP LLCother entity | 3.2M | 7.1% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | Viking Global Opportunities Illiquid Investments Sub-Master LPpartnership | 2.0M | 4.5% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | Viking Global Opportunities Portfolio GP LLCother entity | 2.0M | 4.5% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | Viking Global Opportunities GP LLCother entity | 2.0M | 4.5% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | Viking Global Opportunities Drawdown GP LLCother entity | 1.2M | 2.6% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | Viking Global Opportunities Drawdown (Aggregator) LPpartnership | 1.2M | 2.6% | 2026-03-31 |
| 2026-05-15 | 13G/Ano. 1 | Viking Global Opportunities Drawdown Portfolio GP LLCother entity | 1.2M | 2.6% | 2026-03-31 |
| 2026-05-12 | 13G/Ano. 1 | Q Healthcare Holding LLCinvestment company | 2.0M | 4.5% | 2026-03-31 |
| 2026-05-12 | 13G/Ano. 1 | Qatar Investment Authorityother entity | 2.0M | 4.5% | 2026-03-31 |
| 2026-04-20 | 13D/Ano. 1 | OrbiMed Capital GP VIII LLCother entity | 3.0M | 6.6% | 2026-04-15 |
| 2026-04-20 | 13D/Ano. 1 | ORBIMED ADVISORS LLCinvestment adviser | 3.0M | 6.6% | 2026-04-15 |
| 2025-10-20 | 13D/Ano. 1 | Atlas Venture Fund XI, L.P.partnership | 2.4M | 5.4% | 2025-10-16 |
| 2025-10-20 | 13D/Ano. 1 | Atlas Venture Associates XI, L.P.partnership | 2.4M | 5.4% | 2025-10-16 |
| 2025-10-20 | 13D/Ano. 1 | Atlas Venture Associates XI, LLCother entity | 2.4M | 5.4% | 2025-10-16 |
| 2025-10-20 | 13D/Ano. 1 | Atlas Venture Opportunity Fund II, L.P.partnership | 702K | 1.6% | 2025-10-16 |
| 2025-10-20 | 13D/Ano. 1 | Atlas Venture Associates Opportunity II, LPpartnership | 702K | 1.6% | 2025-10-16 |
| 2025-10-20 | 13D/Ano. 1 | Atlas Venture Associates Opportunity II, LLCother entity | 702K | 1.6% | 2025-10-16 |
13F holders
Tracked managers holding SION at their latest 13F. JSON5 of the 30 tracked managers held SION at their latest 13F, $209.9M 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.
| Fund | Quarter | Shares | Value | Of portfolio | Change in shares |
|---|---|---|---|---|---|
| Viking Global Investors | 2026-06-30 | 3.2M | $140.6M | 0.40% | 0 |
| Citadel Advisors | 2026-06-30 | 1.1M | $50.5M | 0.01% | -19K |
| Millennium Management | 2026-06-30 | 277K | $12.2M | 0.00% | +136K |
| D. E. Shaw & Co. | 2026-06-30 | 102K | $4.5M | 0.00% | new |
| Point72 Asset Management | 2026-06-30 | 49K | $2.2M | 0.00% | -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 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 puts those series for one ticker on one URL, with planned sales, large holders, 13F holders and financials beside them, 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 one-line summary of the latest figures and its own JSON and CSV links, and says when its source last updated.
This page follows Sionna Therapeutics (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 updates
- Short interest
- FINRA consolidated short interestSource: FINRA.Twice a month, about eight business days after settlement. Latest 2026-10-15.JSON and CSV
- Daily short volume
- FINRA Reg SHO daily filesSource: FINRA.Every trading day, the morning after FINRA posts it. Latest 2026-11-03.JSON and CSV
- Fails to deliver
- SEC fails-to-deliver dataSource: SEC.Twice a month, a few weeks after the half month ends. Latest 2026-10-05.JSON and CSV
- Planned sales
- SEC EDGAR Form 144Source: SEC.New notices appear shortly after the SEC posts them; a notice is filed on or before the sale. Latest 2026-09-17.JSON and CSV
- Large holders
- SEC EDGAR Schedule 13D and 13GSource: SEC.New filings appear shortly after the SEC posts them. A 13D is due within five business days of crossing 5%; a 13G follows the passive schedule. Latest 2026-09-21.JSON and CSV
- 13F holders
- SEC EDGAR Form 13F-HRSource: SEC.Quarterly, filed within 45 days of quarter end; 30 tracked managers. Latest 2026-06-30.JSON and CSV
- Earnings dates
- SEC EDGAR 8-K filings (Item 2.02)Source: SEC.Twice a day. Reported dates come from the company's 8-K filings; the next date is marked as an estimate until the 8-K arrives. Latest 2026-08-06.JSON and CSV
- Insider trades
- SEC EDGAR Form 4Source: SEC.New filings appear shortly after the SEC posts them; they're due two business days after the trade. Latest 2026-09-17.JSON and CSV
- Company record
- EDGAR filing index for CIK 2036042Ticker, name and exchange from the SEC's company list, refreshed weekly.
- Rate limits
- 10 requests a minute without a key, 30 with a free key from a free account.
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 large short position are rare and stand out; insider sells next to one 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
Other company pages
Datasets
Frequently Asked Questions
How much of SION is sold short?
3,676,508 shares were held short at the 2026-10-15 settlement, 3.7 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 2026-11-03, 154,534 of the 360,478 SION shares reported to FINRA were sold short, 42.9% 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 2,445 SION shares failed to deliver at settlement 2026-10-05. Fails are reported per settlement date and published twice a month with a lag.
Are SION insiders buying or selling?
Insiders at SION reported 2 open-market sells worth $21.8M in the last 90 days and no open-market buys. Latest filing: McKee Charlotte (CMO and Head of R&D) on 2026-09-17.
Have SION insiders filed to sell?
50 Form 144 notices on file for SION worth $174.3M at the prices reported; 1 in the last 90 days worth $21.8M. Latest: RA Capital Healthcare Fund, L.P. filed on 2026-09-17 to sell 3,448,811 shares ($21.8M) from 2026-09-17.
Who owns 5% or more of SION?
13 holders report 5% or more of SION in their latest filing, 9 on Schedule 13D (active intent). The largest reported stake is Rajeev Shah at 14.3% of the class (6,476,193 shares), filed 2026-09-21 for an event on 2026-09-17.
Which tracked 13F managers own SION?
5 of the 30 tracked 13F managers held SION shares at their latest filing, $209.9M in all. The largest: Andreas Halvorsen's Viking Global Investors (3.2M shares, $140.6M), Ken Griffin's Citadel Advisors (1.1M shares, $50.5M), Izzy Englander's Millennium Management (277K shares, $12.2M), D. E. Shaw & Co. (102K shares, $4.5M), Steve Cohen's Point72 Asset Management (49K shares, $2.2M).
Data on this page is provided for informational purposes only and is not financial advice. See our editorial policy.