Vanguard reports 6.10M-share stake in Quest Diagnostics (DGX) — 5.54%

Rhea-AI Filing Summary

Vanguard Portfolio Management reports beneficial ownership of 6,096,629 shares of Quest Diagnostics Inc. Common Stock (CUSIP 74834L100), representing 5.54% of the class as reported in a Schedule 13G. The filing states sole voting power of 15,229 shares and sole dispositive power over the full 6,096,629 shares. The disclosure is signed by Ashley Grim on 04/29/2026 and describes holdings managed across Vanguard affiliates and funds.

Insights

Institutional Ownership Analyst

Large passive stake disclosed: Vanguard holds 6.10M shares (5.54%) of Quest Diagnostics.

The Schedule 13G shows Vanguard Portfolio Management beneficially owns 6,096,629 shares with sole dispositive power, indicating portfolio management control across Vanguard funds and managed accounts. The filing follows the Investment Company Act of 1940 disclosure practice.

This is a routine institutional ownership disclosure; the filing does not state any planned transactions or changes to holdings. Subsequent filings would be needed to detect active buying/selling or changes to voting arrangements.

Key Figures

Beneficial ownership: 6,096,629 shares Percent of class: 5.54% Sole voting power: 15,229 shares +2 more

5 metrics

Beneficial ownership 6,096,629 shares Amount beneficially owned reported on Schedule 13G

Percent of class 5.54% Percent of common stock reported

Sole voting power 15,229 shares Number with sole power to vote

Filing type Schedule 13G Passive institutional ownership disclosure

Signature date 04/29/2026 Date the form was signed by Ashley Grim

Key Terms

beneficially owned, sole dispositive power, Schedule 13G, Investment Company Act of 1940

4 terms

beneficially owned regulatory

"This reflects the securities beneficially owned, or deemed to be beneficially owned, by Vanguard"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

sole dispositive power regulatory

"Sole power to dispose or to direct the disposition of: 6096629"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

Schedule 13G regulatory

"Item 1. Name of issuer: Quest Diagnostics Inc... Schedule 13G"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

Investment Company Act of 1940 regulatory

"A listing of the shareholders of an investment company registered under the Investment Company Act of 1940"

A U.S. federal law that sets the rulebook for pooled investment vehicles such as mutual funds, exchange-traded funds and similar money managers, requiring them to register with regulators, disclose holdings and fees, limit conflicts of interest, and follow governance standards. It matters to investors because these protections and transparency rules act like a referee and scoreboard, helping people compare funds, trust that managers follow fair practices, and spot hidden costs or risks.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Quest Diagnostics Inc

(Name of Issuer)

Common Stock

(Title of Class of Securities)

74834L100

(CUSIP Number)

03/31/2026

(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): 74834L100

1

Names of Reporting Persons

Vanguard Portfolio Management

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 15,229.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 6,096,629.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,096,629.00

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)

5.54 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: In accordance with SEC Release No. 34-39538 (January 12, 1998), this Schedule 13G reflects the securities beneficially owned, or deemed to be beneficially owned, by Vanguard Portfolio Management LLC and the following affiliates of Vanguard Portfolio Management LLC or business divisions of such affiliates: Vanguard Fiduciary Trust Company and Vanguard Global Advisers, LLC. This Schedule 13G includes securities held by Vanguard funds, or sleeves thereof, over which Vanguard Portfolio Management LLC exercises dispositive power, in addition to securities held by clients over which the affiliates or business divisions of such affiliates indicated above exercise dispositive and/or voting power. This Schedule 13G does not include securities, if any, beneficially owned by other subsidiaries or affiliates of Vanguard Portfolio Management LLC, or business divisions of such subsidiaries whose ownership of securities is disaggregated from that of the reporting business unit in accordance with such release.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Quest Diagnostics Inc
(b)	Address of issuer's principal executive offices: 500 Plaza Drive, Secaucus, NJ, 07094
Item 2.
(a)	Name of person filing: Vanguard Portfolio Management
(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 Number(s): 74834L100
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: 6096629
(b)	Percent of class: 5.54 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 15229
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 6096629
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
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. Vanguard Portfolio Management, 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.

Vanguard Portfolio Management

Signature:	Ashley Grim
Name/Title:	Head of Global Fund Administration
Date:	04/29/2026

FAQ

What stake does Vanguard hold in Quest Diagnostics (DGX)?

Vanguard Portfolio Management reports beneficial ownership of 6,096,629 shares, equal to 5.54% of Quest Diagnostics' common stock, per the Schedule 13G filing.

Does Vanguard have voting control over its DGX shares?

The filing reports sole voting power for 15,229 shares and sole dispositive power over 6,096,629 shares, indicating voting and disposition roles are limited relative to total shares managed.

When was the Schedule 13G for DGX signed?

The disclosure is signed by Ashley Grim, Head of Global Fund Administration, on 04/29/2026, reflecting the reporting date for the beneficial-ownership snapshot.

What does this Schedule 13G filing indicate about Vanguard's intentions?

A Schedule 13G typically indicates a passive institutional holding; the filing lists beneficial ownership and power but does not state any intent to acquire more or to change control, nor does it describe planned transactions.

Which Vanguard entities are referenced in the filing?

The filing states holdings are reported by Vanguard Portfolio Management LLC and affiliates including Vanguard Fiduciary Trust Company and Vanguard Global Advisers, LLC, covering fund and managed-account holdings.