[SCHEDULE 13G/A] TANDEM DIABETES CARE INC Amended Passive Investment Disclosure

Rhea-AI Filing Summary

The Vanguard Group filed Amendment No. 8 to a Schedule 13G/A for Tandem Diabetes Care, reporting 0 shares beneficially owned and 0% of the class as of the filing. The filing explains an internal realignment under SEC Release No. 34-39538 that caused certain subsidiaries or business divisions to report separately. The filing lists The Vanguard Group's address as 100 Vanguard Blvd., Malvern, PA and Tandem's principal executive office as 11075 Roselle Street, San Diego, CA. The form is signed by Ashley Grim, Head of Global Fund Administration on 03/27/2026.

Insights

SEC Filings Analyst

Administrative ownership update noting disaggregation of holdings after Vanguard realignment.

The submission is an amended Schedule 13G/A reporting 0 shares (0%) beneficially owned by The Vanguard Group. It cites SEC Release No. 34-39538 to explain that certain subsidiaries now report separately following an internal reorganization.

Cash‑flow treatment and any prior holdings by specific Vanguard subsidiaries are not detailed in the excerpt; subsequent filings from the named subsidiaries may show their individual positions.

Corporate Governance Expert

Disclosure reflects structural reporting change, not an economic transaction.

The filing attributes the change to an internal realignment and reliance on the cited SEC release to disaggregate beneficial ownership among Vanguard entities. This is a reporting reclassification rather than a sale or acquisition of securities.

Watch for separate 13G/A or 13D filings from Vanguard subsidiaries if investors seek where prior aggregated holdings now appear.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 03/27/2026 - 01:18 PM Learn about SEC filing dates

FAQ

What does The Vanguard Group report for TNDM in Amendment No. 8?

The filing reports 0 shares beneficially owned and 0% of Tandem Diabetes Care common stock. It states the result follows an internal realignment and separate reporting by subsidiaries under a specific SEC release.

Why does the filing mention SEC Release No. 34-39538?

The filing cites SEC Release No. 34-39538 to justify disaggregating beneficial ownership among Vanguard subsidiaries. It says certain divisions will report separately and Vanguard no longer is deemed to beneficially own those securities.

Who signed the Schedule 13G/A amendment for Vanguard?

Ashley Grim, identified as Head of Global Fund Administration, signed the amendment on 03/27/2026, certifying the statements about ownership and the realignment in the filing.

Does this filing indicate Vanguard sold Tandem Diabetes Care shares?

No transaction is described; the filing explains an internal reporting realignment and separate subsidiary reporting. It does not state any sale, purchase, or cash consideration in the provided excerpt.

Where are the issuer and filer addresses listed in the filing?

The issuer's principal executive office is listed as 11075 Roselle Street, San Diego, CA; The Vanguard Group's address is shown as 100 Vanguard Blvd., Malvern, PA in the amendment.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 8)

Tandem Diabetes Care Inc

(Name of Issuer)

Common Stock

(Title of Class of Securities)

875372203

(CUSIP Number)

03/13/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 875372203

1

Names of Reporting Persons

The Vanguard Group

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

PENNSYLVANIA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

0.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: On January 12, 2026, The Vanguard Group, Inc. went through an internal realignment. In accordance with SEC Release No. 34-39538 (January 12, 1998), certain subsidiaries or business divisions of subsidiaries of The Vanguard Group, Inc., that formerly had, or were deemed to have, beneficial ownership with The Vanguard Group, Inc., will report beneficial ownership separately (on a disaggregated basis) from The Vanguard Group, Inc. in reliance on such release. These subsidiaries and/or business divisions pursue the same investment strategies as previously pursued by The Vanguard Group, Inc. prior to the realignment. Further in accordance with SEC Release No. 34-39538 (January 12, 1998), The Vanguard Group, Inc. no longer has, or is deemed to have, beneficial ownership over securities beneficially owned by such subsidiaries and/or business divisions.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Tandem Diabetes Care Inc
(b)	Address of issuer's principal executive offices: 11075 Roselle Street, San Diego, CA, 92121
Item 2.
(a)	Name of person filing: The Vanguard Group
(b)	Address or principal business office or, if none, residence: 100 Vanguard Blvd.,, Malvern, PA, 19355
(c)	Citizenship: PA
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.:
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 0
(b)	Percent of class: 0 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. The Vanguard Group, including investment companies registered under the Investment Company Act of 1940 and other managed accounts, have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities reported herein.No one other person's interest in the securities reported herein is more than 5%.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

The Vanguard Group

Signature:	Ashley Grim
Name/Title:	Head of Global Fund Administration
Date:	03/27/2026