[Form 4] WESTERN DIGITAL CORP Insider Trading Activity

Rhea-AI Filing Summary

Western Digital Corporation (WDC) reported insider equity transactions by its Chief Legal Officer and Corporate Secretary, Cynthia Tregillis. On 11/25/2025, dividend equivalent rights converted into 5 shares of common stock at $0.0, increasing her direct holdings to 148,102 shares. On the same date, 770 shares of common stock were withheld at $155.41 per share to cover tax obligations related to vesting, leaving her with 147,332 directly owned shares. A related derivative position in dividend equivalent rights shows 5.16 underlying common shares involved in the transaction and 276.1717 derivative rights remaining beneficially owned.

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

OMB APPROVAL

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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)
11/25/2025

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	11/25/2025		M		5(1)	A	$0.0	148,102	D
Common Stock	11/25/2025		F		770(2)	D	$155.41	147,332	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)	11/25/2025		M			5.16	(1)	(1)	Common Stock	5.16	$0.0	276.1717	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	11/26/2025
	** 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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did WDC report for Cynthia Tregillis?

WDC reported that Chief Legal Officer and Corporate Secretary Cynthia Tregillis had dividend equivalent rights convert into 5 shares of common stock on 11/25/2025, and that shares were also withheld to cover taxes tied to vesting.

How many Western Digital (WDC) shares does Cynthia Tregillis own after this Form 4?

After the reported transactions, Cynthia Tregillis directly owns 147,332 shares of Western Digital common stock.

Why were 770 WDC shares disposed of in this Form 4 filing?

The 770 shares of WDC common stock were withheld to satisfy a tax obligation arising from the vesting of securities, in accordance with Rule 16b-3(e).

What does the acquisition of 5 WDC shares at $0.0 represent?

The 5 WDC shares acquired at $0.0 reflect the conversion of dividend equivalent rights into common stock on a one-for-one basis when related restricted stock units vested.

What derivative securities related to WDC does Cynthia Tregillis still hold?

She continues to beneficially own 276.1717 dividend equivalent rights, which are derivative securities linked to WDC common stock, following a transaction involving 5.16 underlying shares.

Who signed the WDC Form 4 for Cynthia Tregillis?

The Form 4 was signed by Sandra Garcia as Attorney-in-Fact for Cynthia Tregillis on 11/26/2025.