MannKind CEO shares withheld for RSU taxes

MANNKIND CORP Chief Executive Officer Michael Castagna reported a routine share withholding related to taxes on vested equity.

Rhea-AI Filing Summary

MANNKIND CORP Chief Executive Officer Michael Castagna reported a routine share withholding related to taxes on vested equity. On May 11, 34,957 shares of common stock were withheld at $3.52 per share to satisfy tax withholding obligations from Restricted Stock Units originally granted on May 10, 2022.

These shares were not sold in the open market but used to cover taxes due at vesting. After this transaction, Castagna directly holds 2,442,310 shares of MannKind common stock, which includes 1,356 shares acquired under the company’s Employee Stock Purchase Plan on December 31, 2025.

Insider Trade Summary

Exercise Price or Tax Liability: 34,957 shares

Exercise Price or Tax Liability 1 txn

Insider Castagna Michael

Role Chief Executive Officer

Type	Security	Shares	Price	Value
Exercise Price or Tax Liability	Common Stock, $0.01 Par Value	34,957	$3.52	$123K

Holdings After Transaction: Common Stock, $0.01 Par Value — 2,442,310 shares (Direct)

Footnotes (2)

1. F1. Represents shares withheld to pay tax withholding obligations due on the date of vesting of the Restricted Stock Units originally granted on May 10, 2022.
2. F2. Includes 1,356 shares acquired under the Issuer's Employee Stock Purchase Plan on December 31, 2025.

Key Figures

Shares withheld for taxes: 34,957 shares at $3.52 Shares held after transaction: 2,442,310 shares ESPP shares included: 1,356 shares +1 more

4 metrics

Shares withheld for taxes 34,957 shares at $3.52 Tax withholding on RSU vesting on May 11

Shares held after transaction 2,442,310 shares Direct MannKind common stock holdings following tax withholding

ESPP shares included 1,356 shares Acquired under Employee Stock Purchase Plan on December 31, 2025

Transaction code F Payment of tax liability by delivering securities

Key Terms

Restricted Stock Units, Employee Stock Purchase Plan, tax withholding obligations, Common Stock, $0.01 Par Value

4 terms

Restricted Stock Units financial

"tax withholding obligations due on the date of vesting of the Restricted Stock Units originally granted on May 10, 2022"

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.

Employee Stock Purchase Plan financial

"Includes 1,356 shares acquired under the Issuer's Employee Stock Purchase Plan on December 31, 2025"

An employee stock purchase plan is a company program that lets workers buy shares through small payroll deductions, often at a discount to the market price and after a set offering period. Think of it like a workplace savings plan that turns into ownership: it encourages employees to share in the company’s success and can create predictable buying or selling of stock that investors watch because it affects supply, demand and employee incentives.

tax withholding obligations financial

"Represents shares withheld to pay tax withholding obligations due on the date of vesting"

Common Stock, $0.01 Par Value financial

"security_title: Common Stock, $0.01 Par Value"

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

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Accepted by SEC EDGAR 05/13/2026 - 08:30 PM 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).

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^*

Castagna Michael

(Last) (First) (Middle)

1 CASPER STREET

(Street)

DANBURY CONNECTICUT 06810

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
MANNKIND CORP [ MNKD ]

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

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/11/2026

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, $0.01 Par Value	05/11/2026		F		34,957(1)	D	$3.52	2,442,310(2)	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

Explanation of Responses:

1. Represents shares withheld to pay tax withholding obligations due on the date of vesting of the Restricted Stock Units originally granted on May 10, 2022.

2. Includes 1,356 shares acquired under the Issuer's Employee Stock Purchase Plan on December 31, 2025.

	/s/ Michael Castagna	05/13/2026
	** 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)