SION · Sionna Therapeutics, Inc. · Shareholders & Ownership

$3.60 -0.20 (-5.26%) At close · Oct 23

Russell 2000 member Rebalance outlook locked

Market Cap

$162.76M

45.21M

Volume · Oct 23 918.2K Avg daily vol (3M) 2.24M

Every disclosed holder of SION in one list: 13F institutions, Schedule 13D and 13G filers, insiders (Forms 3, 4 and 5) and registered funds, each from its own latest filing. Holders nest by CIK and SEC reporting links, never by name, and each is summed once.

How the holder list picks a filing →

Who Owns SION

13F quarter Sep 30, 2026, combined view: filers that have not filed yet carry their Jun 30, 2026 positions

No chart: the summed disclosures exceed shares outstanding, so they are not parts of one whole.

Holder group	Holders	Shares	% Out	Summed
Institutional (13F)	153	49,127,957	108.66%	Yes
Insiders (Forms 3, 4, 5)	7	10,242,723	22.65%	Yes
13D/G-only blocks	1	2,020,258	4.47%	Yes
Remaining	—	16,178,539	-35.78%	Negative
Registered funds (N-PORT, not summed)	139	6,683,264	14.78%	No

Shares outstanding: 45,212,399, the issuer's latest cover-page count restated onto today's split basis.

Remaining is negative: the summed disclosures exceed shares outstanding, as when filings are dated at different times or holders that do not disclose their links count the same shares. It is flagged, not clipped.

13D/G-only counts each filer's latest 13D or 13G that no 13F report of the listing contains, that names no 13F filer and that no counted insider files. Funds are never summed: their shares sit inside their advisers' 13F reports.

Holders of SION

One row per holder Every filing By ultimate parent

All 13F Funds Insiders 13D/G Non-US

#	Holder	Shares	% Out	Change	As of	Notes
1	TPG GP A, LLC 13F CIK 1903793 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	6,494,962	14.37%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
1.1	TPG GP A, LLC Insider CIK 1903793 · Jan 22, 2026 Insider, issuer-wide, not summed	6,494,962	14.37%	-250,000	Jan 22, 2026	Insider, issuer-wide, not summed
2	RA CAPITAL MANAGEMENT, L.P. 13D CIK 1346824 · Registered investment adviser · Sep 17, 2026 Item 4 purpose: not restated by this amendment, the earlier 13D's purpose stands not summed	6,476,193	14.32%	-3,595,519	Sep 17, 2026	not summed
2.1	RA CAPITAL MANAGEMENT, L.P. 13F CIK 1346824 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	9,905,045	21.91%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
2.2	RA CAPITAL MANAGEMENT, L.P. Insider CIK 1346824 · Sep 17, 2026 Director, issuer-wide, not summed	6,456,234	14.28%	-3,448,811	Sep 17, 2026	Director, issuer-wide, not summed
3	VIKING GLOBAL INVESTORS LP 13F CIK 1103804 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	3,195,181	7.07%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
4	Atlas Venture Life Science Advisors, LLC 13F CIK 1917529 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	2,995,602	6.63%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
5	Booth Bruce Insider CIK 1451612 · Oct 21, 2025 Director, issuer-wide	2,995,602	6.63%	-88,878	Oct 21, 2025	Director, issuer-wide
6	ENAVATE SCIENCES GP, LLC 13F CIK 1953107 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	2,478,030	5.48%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
7	ORBIMED ADVISORS LLC Insider CIK 1055951 · Jul 7, 2026 10% Owner, issuer-wide, not summed	2,469,959	5.46%	-85,918	Jul 7, 2026	10% Owner, issuer-wide, not summed
7.1	ORBIMED ADVISORS LLC 13F CIK 1055951 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	2,555,877	5.65%	-974,825	Jun 30, 2026	carried, not yet filed for the newest quarter
8	Thompson Peter A. Insider CIK 1357522 · Jul 7, 2026 Director, issuer-wide	2,469,959	5.46%	-85,918	Jul 7, 2026	Director, issuer-wide
9	Atlas Venture Fund XI, L.P. 13D CIK 1708269 · Unknown · Oct 16, 2025 Item 4 purpose: not restated by this amendment, the earlier 13D's purpose stands not summed	2,382,495	5.27%	-503,798	Oct 16, 2025	not summed
9.1	Atlas Venture Fund XI, L.P. Insider CIK 1708269 · Feb 10, 2025 10% Owner, issuer-wide	3,694,020	8.17%	—	Feb 10, 2025	10% Owner, issuer-wide
10	Qatar Investment Authority 13G CIK 1441449 · Unknown · Mar 31, 2026 Rule 13d-1(c), passive investor	2,020,258	4.47%	-189,517	Mar 31, 2026	Rule 13d-1(c), passive investor
11	ADAGE CAPITAL PARTNERS GP, L.L.C. 13F CIK 1165408 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,600,000	3.54%	+1,450,000	Jun 30, 2026	carried, not yet filed for the newest quarter
12	JPMORGAN CHASE & CO 13F CIK 19617 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	1,490,508	3.30%	+25,494	Jun 30, 2026	carried, not yet filed for the newest quarter
13	BlackRock, Inc. 13F CIK 2012383 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	1,474,769	3.26%	+178,902	Jun 30, 2026	carried, not yet filed for the newest quarter
13.1	iShares Russell 2000 ETF Fund S000004344 · Registered fund · Jun 30, 2026 iShares Trust, not summed	483,961	1.07%	+84,092	Jun 30, 2026	iShares Trust, not summed
13.2	iShares Biotechnology ETF Fund S000004350 · Registered fund · Jun 30, 2026 iShares Trust, not summed	185,693	0.41%	+592	Jun 30, 2026	iShares Trust, not summed
13.3	iShares Russell 2000 Growth ETF Fund S000004343 · Registered fund · Jun 30, 2026 iShares Trust, not summed	173,168	0.38%	+41,190	Jun 30, 2026	iShares Trust, not summed
13.4	Master Small Cap Index Series Fund S000002716 · Registered fund · Jun 30, 2026 Quantitative Master Series LLC, not summed	34,469	0.08%	+7,307	Jun 30, 2026	Quantitative Master Series LLC, not summed
13.5	iShares Core S&P Total U.S. Stock Market ETF Fund S000004317 · Registered fund · Jun 30, 2026 iShares Trust, not summed	21,536	0.05%	+544	Jun 30, 2026	iShares Trust, not summed
14	JENNISON ASSOCIATES LLC 13F CIK 53417 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,172,133	2.59%	-279,087	Jun 30, 2026	carried, not yet filed for the newest quarter
15	CITADEL ADVISORS LLC 13F CIK 1423053 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,147,636	2.54%	-19,295	Jun 30, 2026	carried, not yet filed for the newest quarter
16	VANGUARD CAPITAL MANAGEMENT LLC 13F CIK 2100119 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,132,001	2.50%	+102,504	Jun 30, 2026	carried, not yet filed for the newest quarter
17	Y-Intercept (Hong Kong) Ltd 13F CIK 1772875 · Exempt reporting adviser · Sep 30, 2026	1,056,885	2.34%	+1,056,885	Sep 30, 2026
18	STATE STREET CORP 13F CIK 93751 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	1,021,534	2.26%	+265,307	Jun 30, 2026	carried, not yet filed for the newest quarter
18.1	State Street(R) SPDR(R) S&P(R) Biotech ETF Fund S000010018 · Registered fund · Jun 30, 2026 SPDR SERIES TRUST, not summed	647,694	1.43%	+231,064	Jun 30, 2026	SPDR SERIES TRUST, not summed
18.2	STATE STREET SMALL/MID CAP EQUITY INDEX PORTFOLIO Fund S000050332 · Registered fund · Jun 30, 2026 STATE STREET INSTITUTIONAL INVESTMENT TRUST, not summed	6,100	0.01%	+400	Jun 30, 2026	STATE STREET INSTITUTIONAL INVESTMENT TRUST, not summed
18.3	State Street Total Return V.I.S. Fund Fund S000001637 · Registered fund · Jun 30, 2026 STATE STREET VARIABLE INSURANCE SERIES FUNDS INC, not summed	465	0.00%	+100	Jun 30, 2026	STATE STREET VARIABLE INSURANCE SERIES FUNDS INC, not summed
19	VANGUARD TOTAL STOCK MARKET INDEX FUND Fund S000002848 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	934,641	2.07%	+91,700	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
20	PERCEPTIVE ADVISORS LLC 13F CIK 1224962 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	905,000	2.00%	+246,561	Jun 30, 2026	carried, not yet filed for the newest quarter
21	Cloonan Michael Insider CIK 1704336 · Sep 17, 2026 Director, President & CEO, issuer-wide	765,393	1.69%	+218,050	Sep 17, 2026	Director, President & CEO, issuer-wide
22	DEERFIELD MANAGEMENT COMPANY, L.P. 13F CIK 1009258 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	680,916	1.51%	-289,674	Jun 30, 2026	carried, not yet filed for the newest quarter
23	PGIM Jennison Health Sciences Fund Fund S000004380 · Registered fund · May 29, 2026 Prudential Sector Funds, Inc., not summed	651,048	1.44%	0	May 29, 2026	Prudential Sector Funds, Inc., not summed
24	Siren, L.L.C. 13F CIK 2005245 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	610,515	1.35%	+310,515	Jun 30, 2026	carried, not yet filed for the newest quarter
25	JPMorgan Small Cap Growth Fund Fund S000003859 · Registered fund · Jun 30, 2026 JPMorgan Trust II, not summed	524,280	1.16%	-27,549	Jun 30, 2026	JPMorgan Trust II, not summed
26	PRICE T ROWE ASSOCIATES INC /MD/ 13F CIK 80255 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	478,016	1.06%	-278,360	Jun 30, 2026	carried, not yet filed for the newest quarter
26.1	T. Rowe Price Health Sciences Fund, Inc. Fund S000002088 · Registered fund · Jun 30, 2026 T. ROWE PRICE HEALTH SCIENCES FUND, INC., not summed	287,643	0.64%	-259,800	Jun 30, 2026	T. ROWE PRICE HEALTH SCIENCES FUND, INC., not summed
26.2	T. Rowe Price New Horizons Fund, Inc. Fund S000002106 · Registered fund · Jun 30, 2026 T. ROWE PRICE NEW HORIZONS FUND, INC., not summed	70,768	0.16%	—	Jun 30, 2026	T. ROWE PRICE NEW HORIZONS FUND, INC., not summed
26.3	T. Rowe Price Health Sciences Portfolio Fund S000002083 · Registered fund · Jun 30, 2026 T. ROWE PRICE EQUITY SERIES, INC., not summed	17,807	0.04%	-17,900	Jun 30, 2026	T. ROWE PRICE EQUITY SERIES, INC., not summed
26.4	T. Rowe Price Extended Equity Market Index Fund Fund S000002090 · Registered fund · Jun 30, 2026 T. ROWE PRICE INDEX TRUST, INC., not summed	4,438	0.01%	0	Jun 30, 2026	T. ROWE PRICE INDEX TRUST, INC., not summed
26.5	T. Rowe Price Small-Cap Index Fund Fund S000051327 · Registered fund · Jun 30, 2026 T. ROWE PRICE INDEX TRUST, INC., not summed	2,781	0.01%	+955	Jun 30, 2026	T. ROWE PRICE INDEX TRUST, INC., not summed
27	EVENTIDE ASSET MANAGEMENT, LLC 13F CIK 1442891 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	474,981	1.05%	-170,549	Jun 30, 2026	carried, not yet filed for the newest quarter
27.1	Eventide Healthcare & Life Sciences Fund Fund S000039514 · Registered fund · Jun 30, 2026 MUTUAL FUND SERIES TRUST, not summed	474,969	1.05%	-169,555	Jun 30, 2026	MUTUAL FUND SERIES TRUST, not summed
27.2	Eventide Small Cap ETF Fund S000095403 · Registered fund · Jul 31, 2026 Strategy Shares, not summed	12	0.00%	-1,054	Jul 31, 2026	Strategy Shares, not summed
28	GEODE CAPITAL MANAGEMENT, LLC 13F CIK 1214717 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	457,145	1.01%	+67,273	Jun 30, 2026	carried, not yet filed for the newest quarter
29	BAKER BROS. ADVISORS LP 13F CIK 1263508 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	400,000	0.88%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
30	Casdin Capital, LLC 13F CIK 1534261 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	400,000	0.88%	+400,000	Jun 30, 2026	carried, not yet filed for the newest quarter
31	GOLDMAN SACHS GROUP INC 13F CIK 886982 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	388,810	0.86%	+125,636	Jun 30, 2026	carried, not yet filed for the newest quarter
31.1	Goldman Sachs ActiveBeta(R) U.S. Small Cap Equity ETF Fund S000048296 · Registered fund · May 31, 2026 Goldman Sachs ETF Trust, not summed	5,028	0.01%	—	May 31, 2026	Goldman Sachs ETF Trust, not summed
31.2	Goldman Sachs Absolute Return Tracker Fund Fund S000020314 · Registered fund · Aug 31, 2026 GOLDMAN SACHS TRUST, not summed	934	0.00%	-2,054	Aug 31, 2026	GOLDMAN SACHS TRUST, not summed
32	Driehaus Capital Management LLC 13F CIK 938206 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	385,447	0.85%	+308,814	Jun 30, 2026	carried, not yet filed for the newest quarter
32.1	Driehaus Micro Cap Growth Fund Fund S000042829 · Registered fund · Jun 30, 2026 Driehaus Mutual Funds, not summed	46,945	0.10%	—	Jun 30, 2026	Driehaus Mutual Funds, not summed
33	FRANKLIN RESOURCES INC 13F CIK 38777 · Investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	290,113	0.64%	+114,630	Jun 30, 2026	carried, not yet filed for the newest quarter
33.1	Franklin Biotechnology Discovery Fund Fund S000006882 · Registered fund · Jul 31, 2026 Franklin Strategic Series, not summed	107,956	0.24%	+47,065	Jul 31, 2026	Franklin Strategic Series, not summed
34	Aberdeen Group plc 13F CIK 1716774 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	284,138	0.63%	-280,037	Jun 30, 2026	carried, not yet filed for the newest quarter
35	FMR LLC 13F CIK 315066 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	278,292	0.62%	+196,897	Jun 30, 2026	carried, not yet filed for the newest quarter
35.1	Fidelity Small Cap Index Fund Fund S000033638 · Registered fund · Jul 31, 2026 Fidelity Salem Street Trust, not summed	201,838	0.45%	+41,098	Jul 31, 2026	Fidelity Salem Street Trust, not summed
35.2	Select Biotechnology Portfolio Fund S000007486 · Registered fund · May 31, 2026 Fidelity Select Portfolios, not summed	80,900	0.18%	—	May 31, 2026	Fidelity Select Portfolios, not summed
35.3	Fidelity Extended Market Index Fund Fund S000006021 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	73,777	0.16%	-1,338	May 31, 2026	Fidelity Concord Street Trust, not summed
35.4	Fidelity Nasdaq Composite Index Fund Fund S000055366 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	27,764	0.06%	0	May 31, 2026	Fidelity Concord Street Trust, not summed
35.5	Fidelity Total Market Index Fund Fund S000006026 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	26,184	0.06%	0	May 31, 2026	Fidelity Concord Street Trust, not summed
36	MILLENNIUM MANAGEMENT LLC 13F CIK 1273087 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	276,733	0.61%	+136,092	Jun 30, 2026	carried, not yet filed for the newest quarter
37	Candriam S.C.A. 13F CIK 1537014 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	233,208	0.52%	-3,605	Jun 30, 2026	carried, not yet filed for the newest quarter
38	VANGUARD PORTFOLIO MANAGEMENT LLC 13F CIK 2100121 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	222,949	0.49%	+80,868	Jun 30, 2026	carried, not yet filed for the newest quarter
39	Kalehua Capital Management LLC 13F CIK 2106181 · Exempt reporting adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	197,072	0.44%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
40	Longaeva Partners L.P. 13F CIK 2054122 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	196,352	0.43%	+183,659	Jun 30, 2026	carried, not yet filed for the newest quarter
41	Artisan Partners Limited Partnership 13F CIK 1466153 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	189,498	0.42%	+189,498	Jun 30, 2026	carried, not yet filed for the newest quarter
41.1	Artisan International Small-Mid Fund Fund S000006494 · Registered fund · Jun 30, 2026 Artisan Partners Funds Inc., not summed	116,442	0.26%	—	Jun 30, 2026	Artisan Partners Funds Inc., not summed
42	Ensign Peak Advisors, Inc 13F CIK 1454984 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	184,532	0.41%	-71,104	Jun 30, 2026	carried, not yet filed for the newest quarter
43	Soleus Capital Management, L.P. 13F CIK 1802630 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	177,687	0.39%	-115,813	Jun 30, 2026	carried, not yet filed for the newest quarter
44	VANGUARD EXTENDED MARKET INDEX FUND Fund S000002841 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	168,369	0.37%	+8,864	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
45	JPMorgan Small Cap Blend Fund Fund S000002767 · Registered fund · Jun 30, 2026 JPMorgan Trust I, not summed	166,643	0.37%	-11,508	Jun 30, 2026	JPMorgan Trust I, not summed
46	NORTHERN TRUST CORP 13F CIK 73124 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	154,476	0.34%	+37,700	Jun 30, 2026	carried, not yet filed for the newest quarter
46.1	Small Cap Index Fund Fund S000001245 · Registered fund · Jun 30, 2026 Northern Funds, not summed	9,298	0.02%	+2,126	Jun 30, 2026	Northern Funds, not summed
46.2	Small Cap Core Fund Fund S000001244 · Registered fund · Jun 30, 2026 Northern Funds, not summed	4,219	0.01%	—	Jun 30, 2026	Northern Funds, not summed
47	MORGAN STANLEY 13F CIK 895421 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	151,047	0.33%	+18,024	Jun 30, 2026	carried, not yet filed for the newest quarter
48	Sofinnova Investments, Inc. 13F CIK 1631134 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	144,432	0.32%	+144,432	Jun 30, 2026	carried, not yet filed for the newest quarter
49	Qube Research & Technologies Ltd 13F CIK 1729829 · Exempt reporting adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	140,309	0.31%	+98,067	Jun 30, 2026	carried, not yet filed for the newest quarter
50	Alyeska Investment Group, L.P. 13F CIK 1453072 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	136,222	0.30%	0	Jun 30, 2026	carried, not yet filed for the newest quarter

16 more nested rows are not shown here; Every filing lists them all.

Shares are restated onto today's split basis. Change compares each row with the same holder's previous filing in the same source; a dash means there is none to compare. Nested 13D/G, insider and fund rows are not summed, since a 13F report already holds them.

Showing 1–50 of 228 holders

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Key facts CIK 2036042 CUSIP 829401108 13F (30d) 14 filings 14 filers Visit website Investor relations