[Form 4] WESTERN DIGITAL CORP Insider Trading Activity

Rhea-AI Filing Summary

Western Digital Corp (WDC) reported insider equity activity by its Chief Legal Officer and Corporate Secretary, Cynthia Tregillis, in a Form 4. On 11/20/2025 and 11/21/2025, dividend equivalent rights tied to restricted stock units were converted on a one-for-one basis into shares of Western Digital common stock at an exercise price of $0.0, increasing her direct holdings.

On the same dates, shares of common stock were withheld to cover tax obligations related to the vesting of these equity awards, at prices of $140.23 for 379 shares and $139.19 for 1,108 shares. After these transactions, Tregillis directly held 148,097 shares of Western Digital common stock and 281.3317 dividend equivalent rights.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Tregillis Cynthia L

(Last) (First) (Middle)

C/O WESTERN DIGITAL CORPORATION

5601 GREAT OAKS PARKWAY

(Street)

SAN JOSE CA 95119

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
WESTERN DIGITAL CORP [ WDC ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Legal Officer & Corp Sec

3. Date of Earliest Transaction (Month/Day/Year)
11/20/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/20/2025		M		2(1)	A	$0.0	149,577	D
Common Stock	11/20/2025		F		379(2)	D	$140.23	149,198	D
Common Stock	11/21/2025		M		7(1)	A	$0.0	149,205	D
Common Stock	11/21/2025		F		1,108(2)	D	$139.19	148,097	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Dividend Equivalent Rights	(1)	11/20/2025		M			2.5444	(1)	(1)	Common Stock	2.5444	$0.0	288.7586	D
Dividend Equivalent Rights	(1)	11/21/2025		M			7.4269	(1)	(1)	Common Stock	7.4269	$0.0	281.3317	D

Explanation of Responses:

1. The dividend equivalent rights were converted into, and paid in the form of, shares of the Issuer's common stock on a one-for-one basis in connection with the vesting of restricted stock units to which the dividend equivalent rights relate. A cash amount was also paid to the holder to settle a fractional dividend equivalent right.

2. Payment of tax obligation by withholding securities incident to the vesting of securities in accordance with Rule 16b-3(e).

	By: /s/ Sandra Garcia Attorney-in-Fact For: Cynthia Tregillis	11/24/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

What insider transaction did WDC report for Cynthia Tregillis?

Western Digital reported that Cynthia Tregillis, its Chief Legal Officer and Corporate Secretary, had dividend equivalent rights convert into common stock and had shares withheld to satisfy tax obligations related to equity vesting.

How many Western Digital shares were used to cover taxes for Cynthia Tregillis?

Shares of 379 at $140.23 on 11/20/2025 and 1,108 at $139.19 on 11/21/2025 were withheld to pay tax obligations in connection with vesting securities.

What are dividend equivalent rights in this WDC Form 4?

The filing states that dividend equivalent rights were converted into, and paid in the form of, shares of Western Digital common stock on a one-for-one basis when related restricted stock units vested.

How many Western Digital shares does Cynthia Tregillis hold after these transactions?

After the reported transactions, Cynthia Tregillis directly beneficially owned 148,097 shares of Western Digital common stock.

Did Cynthia Tregillis retain any derivative rights after the reported WDC transactions?

Yes. Following the transactions, she held 281.3317 dividend equivalent rights, each tied to Western Digital common stock.

What role does Cynthia Tregillis hold at Western Digital (WDC)?

Cynthia Tregillis is identified as an Officer of Western Digital, serving as Chief Legal Officer & Corporate Secretary.