TNDM · Tandem Diabetes Care Inc · Shareholders & Ownership

$16.35 -0.17 (-1.03%) At close · Oct 21

S&P 600 member Russell 2000 member Rebalance outlook locked

Market Cap

$1.16B

69.58M

Volume · Oct 21 1.53M Avg daily vol (3M) 2.03M

Every disclosed holder of TNDM 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 TNDM

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)	269	78,472,265	112.78%	Yes
Insiders (Forms 3, 4, 5)	17	859,505	1.24%	Yes
13D/G-only blocks	3	7,880,695	11.33%	Yes
Remaining	—	17,633,758	-25.34%	Negative
Registered funds (N-PORT, not summed)	214	26,044,721	37.43%	No

Shares outstanding: 69,578,707, 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 TNDM

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	BlackRock, Inc. 13F CIK 2012383 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	11,583,125	16.65%	+892,281	Jun 30, 2026	carried, not yet filed for the newest quarter
1.1	iShares Core S&P Small-Cap ETF Fund S000004313 · Registered fund · Jun 30, 2026 iShares Trust, not summed	4,129,585	5.94%	+60,565	Jun 30, 2026	iShares Trust, not summed
1.2	iShares Russell 2000 ETF Fund S000004344 · Registered fund · Jun 30, 2026 iShares Trust, not summed	1,818,684	2.61%	+159,687	Jun 30, 2026	iShares Trust, not summed
1.3	iShares Russell 2000 Growth ETF Fund S000004343 · Registered fund · Jun 30, 2026 iShares Trust, not summed	644,820	0.93%	+90,728	Jun 30, 2026	iShares Trust, not summed
1.4	iShares S&P Small-Cap 600 Growth ETF Fund S000004314 · Registered fund · Jun 30, 2026 iShares Trust, not summed	342,705	0.49%	+15,499	Jun 30, 2026	iShares Trust, not summed
1.5	iShares U.S. Medical Devices ETF Fund S000009419 · Registered fund · Jun 30, 2026 iShares Trust, not summed	320,911	0.46%	+29,336	Jun 30, 2026	iShares Trust, not summed
2	Sessa Capital IM, L.P. 13F CIK 1595849 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	5,100,000	7.33%	+369,243	Jun 30, 2026	carried, not yet filed for the newest quarter
3	Sessa Capital (Master), L.P. 13G CIK 1618360 · Unknown · Mar 31, 2025 Rule 13d-1(c), passive investor	4,466,307	6.42%	—	Mar 31, 2025	Rule 13d-1(c), passive investor
4	VANGUARD PORTFOLIO MANAGEMENT LLC 13F CIK 2100121 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	4,299,667	6.18%	+306,334	Jun 30, 2026	carried, not yet filed for the newest quarter
5	First Light Asset Management, LLC 13F CIK 1600004 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	3,383,553	4.86%	+2,068,838	Jun 30, 2026	carried, not yet filed for the newest quarter
6	Capital World Investors 13G CIK 1422849 · Investment adviser · Aug 30, 2024 Rule 13d-1(b), qualified institution	3,265,300	4.69%	-3,271,478	Aug 30, 2024	Rule 13d-1(b), qualified institution
7	VANGUARD CAPITAL MANAGEMENT LLC 13F CIK 2100119 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	3,096,536	4.45%	+57,617	Jun 30, 2026	carried, not yet filed for the newest quarter
8	STATE STREET CORP 13F CIK 93751 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	2,851,646	4.10%	+189,386	Jun 30, 2026	carried, not yet filed for the newest quarter
8.1	State Street(R) SPDR(R) Portfolio S&P 600(TM) Small Cap ETF Fund S000041317 · Registered fund · Jun 30, 2026 SPDR SERIES TRUST, not summed	627,958	0.90%	+8,861	Jun 30, 2026	SPDR SERIES TRUST, not summed
8.2	State Street(R) SPDR(R) S & P 600(TM) Small Cap Growth ETF Fund S000006990 · Registered fund · Jun 30, 2026 SPDR SERIES TRUST, not summed	204,353	0.29%	+4,055	Jun 30, 2026	SPDR SERIES TRUST, not summed
8.3	State Street(R) SPDR(R) S & P 600(TM) Small Cap Value ETF Fund S000006974 · Registered fund · Jun 30, 2026 SPDR SERIES TRUST, not summed	160,544	0.23%	+4,928	Jun 30, 2026	SPDR SERIES TRUST, not summed
8.4	State Street(R) SPDR(R) S&P(R) Health Care Equipment ETF Fund S000012330 · Registered fund · Jun 30, 2026 SPDR SERIES TRUST, not summed	152,433	0.22%	+46,304	Jun 30, 2026	SPDR SERIES TRUST, not summed
8.5	STATE STREET SMALL/MID CAP EQUITY INDEX PORTFOLIO Fund S000050332 · Registered fund · Jun 30, 2026 STATE STREET INSTITUTIONAL INVESTMENT TRUST, not summed	23,592	0.03%	0	Jun 30, 2026	STATE STREET INSTITUTIONAL INVESTMENT TRUST, not summed
9	GW&K Investment Management, LLC 13F CIK 1082917 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	2,569,032	3.69%	-120,074	Jun 30, 2026	carried, not yet filed for the newest quarter
10	JENNISON ASSOCIATES LLC 13F CIK 53417 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	2,331,429	3.35%	+672,981	Jun 30, 2026	carried, not yet filed for the newest quarter
11	VANGUARD TOTAL STOCK MARKET INDEX FUND Fund S000002848 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	2,186,918	3.14%	+28,917	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
12	Paradice Investment Management LLC 13F CIK 1620275 · Registered investment adviser · Sep 30, 2026	2,007,415	2.89%	-16,599	Sep 30, 2026
13	JACOBS LEVY EQUITY MANAGEMENT, INC 13F CIK 884414 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	2,006,429	2.88%	+482,483	Jun 30, 2026	carried, not yet filed for the newest quarter
14	Freestone Grove Partners LP 13F CIK 2007591 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,866,134	2.68%	+535,392	Jun 30, 2026	carried, not yet filed for the newest quarter
15	GEODE CAPITAL MANAGEMENT, LLC 13F CIK 1214717 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,800,797	2.59%	+120,934	Jun 30, 2026	carried, not yet filed for the newest quarter
16	Driehaus Capital Management LLC 13F CIK 938206 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,786,996	2.57%	-517,418	Jun 30, 2026	carried, not yet filed for the newest quarter
16.1	Driehaus Micro Cap Growth Fund Fund S000042829 · Registered fund · Jun 30, 2026 Driehaus Mutual Funds, not summed	188,224	0.27%	-66,323	Jun 30, 2026	Driehaus Mutual Funds, not summed
17	CITADEL ADVISORS LLC 13F CIK 1423053 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,735,879	2.49%	-456,788	Jun 30, 2026	carried, not yet filed for the newest quarter
18	VANGUARD SMALL-CAP INDEX FUND Fund S000002845 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	1,570,019	2.26%	-4,321	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
19	MILLENNIUM MANAGEMENT LLC 13F CIK 1273087 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,311,739	1.89%	+550,067	Jun 30, 2026	carried, not yet filed for the newest quarter
20	Woodline Partners LP 13F CIK 1784547 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,307,439	1.88%	+1,307,439	Jun 30, 2026	carried, not yet filed for the newest quarter
21	ArrowMark Colorado Holdings LLC 13F CIK 1483859 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,299,586	1.87%	-1,804,023	Jun 30, 2026	carried, not yet filed for the newest quarter
21.1	Meridian Growth Fund Fund S000001462 · Registered fund · Jun 30, 2026 Meridian Fund Inc, not summed	483,102	0.69%	-13,470	Jun 30, 2026	Meridian Fund Inc, not summed
21.2	Meridian Small Cap Growth Fund Fund S000042770 · Registered fund · Jun 30, 2026 Meridian Fund Inc, not summed	274,345	0.39%	0	Jun 30, 2026	Meridian Fund Inc, not summed
21.3	Meridian Contrarian Fund Fund S000001463 · Registered fund · Jun 30, 2026 Meridian Fund Inc, not summed	159,000	0.23%	0	Jun 30, 2026	Meridian Fund Inc, not summed
22	UBS Group AG 13F CIK 1610520 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	1,146,580	1.65%	-901,221	Jun 30, 2026	carried, not yet filed for the newest quarter
23	FMR LLC 13F CIK 315066 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	976,432	1.40%	+262,421	Jun 30, 2026	carried, not yet filed for the newest quarter
23.1	Fidelity Small Cap Index Fund Fund S000033638 · Registered fund · Jul 31, 2026 Fidelity Salem Street Trust, not summed	763,465	1.10%	+92,773	Jul 31, 2026	Fidelity Salem Street Trust, not summed
23.2	Strategic Advisers Fidelity U.S. Total Stock Fund Fund S000061481 · Registered fund · May 31, 2026 Fidelity Rutland Square Trust II, not summed	476,900	0.69%	0	May 31, 2026	Fidelity Rutland Square Trust II, not summed
23.3	Fidelity Enhanced Small Cap Core ETF Fund S000081807 · Registered fund · Jun 30, 2026 Fidelity Covington Trust, not summed	360,810	0.52%	+152,596	Jun 30, 2026	Fidelity Covington Trust, not summed
23.4	Fidelity Extended Market Index Fund Fund S000006021 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	351,589	0.51%	+34,766	May 31, 2026	Fidelity Concord Street Trust, not summed
23.5	Fidelity Total Market Index Fund Fund S000006026 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	128,235	0.18%	+2,507	May 31, 2026	Fidelity Concord Street Trust, not summed
24	VANGUARD SMALL-CAP GROWTH INDEX FUND Fund S000002846 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	901,467	1.30%	+22,344	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
25	ROYCE & ASSOCIATES LP 13F CIK 906304 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	900,590	1.29%	+204,000	Jun 30, 2026	carried, not yet filed for the newest quarter
25.1	Royce Small-Cap Opportunity Fund Fund S000009512 · Registered fund · Jun 30, 2026 ROYCE FUND, not summed	423,694	0.61%	+64,698	Jun 30, 2026	ROYCE FUND, not summed
26	WELLINGTON MANAGEMENT GROUP LLP 13F CIK 902219 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	871,811	1.25%	-170,953	Jun 30, 2026	carried, not yet filed for the newest quarter
27	GOLDMAN SACHS GROUP INC 13F CIK 886982 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	862,301	1.24%	-1,356,621	Jun 30, 2026	carried, not yet filed for the newest quarter
27.1	Goldman Sachs ActiveBeta(R) U.S. Small Cap Equity ETF Fund S000048296 · Registered fund · May 31, 2026 Goldman Sachs ETF Trust, not summed	54,329	0.08%	-2,555	May 31, 2026	Goldman Sachs ETF Trust, not summed
27.2	Goldman Sachs Multi-Manager Global Equity Fund Fund S000049146 · Registered fund · Jul 31, 2026 Goldman Sachs Trust II, not summed	21,352	0.03%	-3,316	Jul 31, 2026	Goldman Sachs Trust II, not summed
27.3	Goldman Sachs Small Cap Equity Insights Fund Fund S000009329 · Registered fund · Jul 31, 2026 Goldman Sachs Trust, not summed	20,819	0.03%	—	Jul 31, 2026	Goldman Sachs Trust, not summed
27.4	Goldman Sachs Innovate Equity ETF Fund S000068597 · Registered fund · May 31, 2026 Goldman Sachs ETF Trust, not summed	11,077	0.02%	+1,355	May 31, 2026	Goldman Sachs ETF Trust, not summed
27.5	Multi-Manager U.S. Small Cap Equity Fund Fund S000051363 · Registered fund · Apr 30, 2026 Goldman Sachs Trust II, not summed	7,744	0.01%	—	Apr 30, 2026	Goldman Sachs Trust II, not summed
28	VANGUARD EXTENDED MARKET INDEX FUND Fund S000002841 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	788,509	1.13%	+31,756	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
29	NORTHERN TRUST CORP 13F CIK 73124 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	753,690	1.08%	+47,081	Jun 30, 2026	carried, not yet filed for the newest quarter
29.1	Small Cap Index Fund Fund S000001245 · Registered fund · Jun 30, 2026 Northern Funds, not summed	35,361	0.05%	+4,436	Jun 30, 2026	Northern Funds, not summed
29.2	Small Cap Core Fund Fund S000001244 · Registered fund · Jun 30, 2026 Northern Funds, not summed	5,953	0.01%	-265	Jun 30, 2026	Northern Funds, not summed
29.3	FlexShares Morningstar US Market Factor Tilt Index Fund Fund S000033312 · Registered fund · Jul 31, 2026 FlexShares Trust, not summed	2,592	0.00%	+128	Jul 31, 2026	FlexShares Trust, not summed
30	Verition Fund Management LLC 13F CIK 1454027 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	700,000	1.01%	+592,881	Jun 30, 2026	carried, not yet filed for the newest quarter
31	ExodusPoint Capital Management, LP 13F CIK 1736225 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	691,789	0.99%	+58,890	Jun 30, 2026	carried, not yet filed for the newest quarter
32	Qube Research & Technologies Ltd 13F CIK 1729829 · Exempt reporting adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	683,823	0.98%	+631,862	Jun 30, 2026	carried, not yet filed for the newest quarter
33	D. E. Shaw & Co., Inc. 13F CIK 1009207 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	681,808	0.98%	-102,098	Jun 30, 2026	carried, not yet filed for the newest quarter
34	PGIM Jennison Health Sciences Fund Fund S000004380 · Registered fund · May 29, 2026 Prudential Sector Funds, Inc., not summed	680,031	0.98%	+183,735	May 29, 2026	Prudential Sector Funds, Inc., not summed
35	ARROWSTREET CAPITAL, LIMITED PARTNERSHIP 13F CIK 1164508 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	667,689	0.96%	+474,133	Jun 30, 2026	carried, not yet filed for the newest quarter
36	CHARLES SCHWAB INVESTMENT MANAGEMENT INC 13F CIK 884546 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	656,836	0.94%	+14,238	Jun 30, 2026	carried, not yet filed for the newest quarter
36.1	Schwab U.S. Small-Cap ETF Fund S000026636 · Registered fund · May 31, 2026 SCHWAB STRATEGIC TRUST, not summed	328,035	0.47%	+415	May 31, 2026	SCHWAB STRATEGIC TRUST, not summed
36.2	Schwab Small-Cap Index Fund Fund S000005912 · Registered fund · Jul 31, 2026 SCHWAB CAPITAL TRUST, not summed	169,004	0.24%	+19,975	Jul 31, 2026	SCHWAB CAPITAL TRUST, not summed
36.3	Schwab Total Stock Market Index Fund Fund S000005913 · Registered fund · Jul 31, 2026 SCHWAB CAPITAL TRUST, not summed	41,337	0.06%	0	Jul 31, 2026	SCHWAB CAPITAL TRUST, not summed
36.4	Schwab U.S. Broad Market ETF Fund S000026631 · Registered fund · May 31, 2026 SCHWAB STRATEGIC TRUST, not summed	39,684	0.06%	+479	May 31, 2026	SCHWAB STRATEGIC TRUST, not summed
37	MORGAN STANLEY 13F CIK 895421 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	647,069	0.93%	-710,473	Jun 30, 2026	carried, not yet filed for the newest quarter
37.1	E*TRADE No Fee Total Market Index Fund Fund S000090722 · Registered fund · Jul 31, 2026 E Trade Trust, not summed	21	0.00%	0	Jul 31, 2026	E Trade Trust, not summed
38	Point72 Asset Management, L.P. 13F CIK 1603466 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	610,903	0.88%	+190,425	Jun 30, 2026	carried, not yet filed for the newest quarter
39	Soleus Capital Management, L.P. 13F CIK 1802630 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	575,000	0.83%	-208,000	Jun 30, 2026	carried, not yet filed for the newest quarter
40	BANK OF MONTREAL /CAN/ 13F CIK 927971 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	564,966	0.81%	+527,531	Jun 30, 2026	carried, not yet filed for the newest quarter
41	TWO SIGMA INVESTMENTS, LP 13F CIK 1179392 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	558,409	0.80%	-1,305,785	Jun 30, 2026	carried, not yet filed for the newest quarter
42	AQR CAPITAL MANAGEMENT LLC 13F CIK 1167557 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	533,837	0.77%	+201,921	Jun 30, 2026	carried, not yet filed for the newest quarter
43	VANGUARD FIDUCIARY TRUST CO 13F CIK 933478 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	491,103	0.71%	+19,445	Jun 30, 2026	carried, not yet filed for the newest quarter
44	VANGUARD TAX-MANAGED SMALL-CAP FUND Fund S000004387 · Registered fund · Jun 30, 2026 VANGUARD TAX-MANAGED FUNDS, not summed	454,971	0.65%	0	Jun 30, 2026	VANGUARD TAX-MANAGED FUNDS, not summed
45	Aberdeen Group plc 13F CIK 1716774 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	441,738	0.63%	+7,711	Jun 30, 2026	carried, not yet filed for the newest quarter
46	Jump Financial, LLC 13F CIK 1831577 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	404,400	0.58%	+404,400	Jun 30, 2026	carried, not yet filed for the newest quarter
47	BANK OF AMERICA CORP /DE/ 13F CIK 70858 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	395,054	0.57%	+21,830	Jun 30, 2026	carried, not yet filed for the newest quarter
48	FRONTIER CAPITAL MANAGEMENT CO LLC 13F CIK 351173 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	380,458	0.55%	-16,751	Jun 30, 2026	carried, not yet filed for the newest quarter
49	TUDOR INVESTMENT CORP ET AL 13F CIK 923093 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	362,708	0.52%	+283,709	Jun 30, 2026	carried, not yet filed for the newest quarter
50	DAFNA Capital Management LLC 13F CIK 1389933 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	355,208	0.51%	0	Jun 30, 2026	carried, not yet filed for the newest quarter

38 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 397 holders

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Key facts CIK 1438133 CUSIP 875372203 13F (30d) 28 filings 27 filers Visit website Investor relations