Western Digital’s Tregillis sells 807 shares at $380

Western Digital Corp. Chief Legal Officer & Corp Sec Cynthia L. Tregillis sold 807 shares of common stock on October 21, 2026, at $380.00 per share under a Rule 10b5-1 trading plan adopted on March 6, 2026.

Rhea-AI Filing Summary

Western Digital Corp. Chief Legal Officer & Corp Sec Cynthia L. Tregillis sold 807 shares of common stock on October 21, 2026, at $380.00 per share under a Rule 10b5-1 trading plan adopted on March 6, 2026. On October 20, dividend equivalent rights converted into 14 shares of common stock on a one-for-one basis in connection with restricted stock unit vesting, and 1,310 shares were withheld for the related tax obligation.

Insider Trade Summary 10b5-1

Exercise and sale activity reported; no spread calculated

Exercise and Sale 4 txns

Insider Tregillis Cynthia L

Role Chief Legal Officer & Corp Sec

Sold 807 shs ($307K)

Approx. gross sale proceeds $307K

Type	Security	Shares	Price	Value
Sale	Common Stock F3	807	$380.00	$307K
Exercise	Dividend Equivalent Rights F1	14.3704	$0.00	$0.00
Exercise	Common Stock F1	14.37	$0.00	$0.00
Tax Withholding	Common Stock F2	1,309.713	$364.32	$477K

Holdings After Transaction: Dividend Equivalent Rights — 283.4915 contracts (Direct); Common Stock — 108,927.657 shares (Direct)

Footnotes (3)

1. F1. 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. F2. Payment of tax obligation by withholding securities incident to the vesting of securities in accordance with Rule 16b-3(e).
3. F3. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 6, 2026.

Key Figures

Common shares sold: 807 shares Sale price: $380.00 per share Common shares acquired upon conversion: 14 shares +1 more

4 metrics

Common shares sold 807 shares October 21, 2026

Sale price $380.00 per share October 21, 2026

Common shares acquired upon conversion 14 shares October 20, 2026; dividend equivalent rights converted one-for-one

Shares withheld for tax obligation 1,310 shares October 20, 2026; incident to vesting of securities

Key Terms

Rule 10b5-1 trading plan, dividend equivalent rights, restricted stock units, Rule 16b-3(e)

4 terms

Rule 10b5-1 trading plan regulatory

"effected pursuant to a Rule 10b5-1 trading plan"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

dividend equivalent rights financial

"dividend equivalent rights were converted into"

Dividend equivalent rights are promises that mirror the cash payments shareholders get from a company’s profits, but they are paid to holders of certain awards (like stock options or restricted stock units) rather than to actual shares. Think of them as a paycheck top‑up that matches dividends while the award is not yet a real stock, and they matter to investors because they add to employee compensation costs and potential share dilution, affecting company profitability and per‑share value.

restricted stock units financial

"vesting of restricted stock units to which the dividend equivalent rights relate"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

Rule 16b-3(e) regulatory

"in accordance with Rule 16b-3(e)"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many WDC shares did Chief Legal Officer & Corp Sec Cynthia L. Tregillis sell, and at what price?

Chief Legal Officer & Corp Sec Cynthia L. Tregillis sold 807 shares on October 21, 2026, at $380.00 per share. The sale was made under a Rule 10b5-1 trading plan adopted on March 6, 2026.

What happened to Cynthia L. Tregillis's fractional dividend equivalent right?

A cash amount was paid to settle the fractional dividend equivalent right.

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

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Available on EDGAR 10/22/2026 - 05:57 PM EDT Accepted by SEC EDGAR 10/22/2026 - 05:57 PM EDT Learn about SEC filing dates

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

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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

X

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 CALIFORNIA 95119

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
10/20/2026

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

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

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

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	10/20/2026		M		14.37(1)	A	$0.0	111,044.37	D
Common Stock	10/20/2026		F		1,309.713(2)	D	$364.32	109,734.657	D
Common Stock	10/21/2026		S(3)		807	D	$380	108,927.657	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)	10/20/2026		M			14.3704	(1)	(1)	Common Stock	14.3704	$0.0	283.4915	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).

3. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 6, 2026.

	By: /s/ Sandra Garcia Attorney-in-Fact For: Cynthia Tregillis	10/22/2026
	** 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.
* Form 4: SEC 1474 (03-26)