MannKind (MNKD) CEO clarifies 100,000-share Form 4 error in amendment

Rhea-AI Filing Summary

MANNKIND CORP Chief Executive Officer Michael Castagna filed an amended insider report clarifying that a previously filed Form 4 was erroneous. The earlier Form 4 had mistakenly shown him directly acquiring 100,000 MannKind common shares on March 10, 2026.

The amendment explains these shares were actually acquired by his spouse in a segregated retirement account in which he has no pecuniary interest, so the transaction should not be attributed to him and the prior Form 4 should be deemed revoked. As of March 10, 2026, he is reported as directly owning 2,475,911 MannKind common shares.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Castagna Michael

Role Chief Executive Officer

Type	Security	Shares	Price	Value
holding	Common Stock $0.01 Par Value	--	--	--

Holdings After Transaction: Common Stock $0.01 Par Value — 2,475,911 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Directly owned shares: 2,475,911 shares Erroneously reported acquisition: 100,000 shares

2 metrics

Directly owned shares 2,475,911 shares Common stock directly owned as of March 10, 2026

Erroneously reported acquisition 100,000 shares Prior Form 4 mistakenly reported as acquired by Michael Castagna

Key Terms

Form 4, pecuniary interest, segregated retirement account, Section 16(a)

4 terms

Form 4 regulatory

"Mr. Castagna filed a Form 4 that should not have been filed"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

pecuniary interest financial

"a segregated retirement account in which Mr. Castagna does not have a pecuniary interest"

segregated retirement account financial

"acquired by Mr. Castagna's spouse under a segregated retirement account"

Section 16(a) regulatory

"As a result, Mr. Castagna was not obligated to file a Form 4 pursuant to Section 16(a)."

Form 4 Insider Transactions: What Each Field Means →

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)
03/10/2026

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)
03/10/2026

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								2,475,911(1)	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. On March 10, 2026 Mr. Castagna filed a Form 4 that should not have been filed and which reported a transaction that should not, in fact, be attributable to him. The Form 4 mistakenly reported a direct acquisition of 100,000 shares of common stock of the Issuer on March 10, 2026 by Mr. Castagna (the "Shares"). The Shares, however, were acquired by Mr. Castagna's spouse under a segregated retirement account in which Mr. Castagna does not have a pecuniary interest. As a result, Mr. Castagna was not obligated to file a Form 4 pursuant to Section 16(a). Such Form 4 should be deemed revoked.

	/s/ Michael Castagna	05/08/2026
	** 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)

FAQ

What does MannKind (MNKD) CEO Michael Castagna’s amended Form 4 report?

The amended Form 4 states that an earlier filing incorrectly reported Michael Castagna directly acquiring 100,000 MannKind shares. It clarifies the shares were bought by his spouse in a segregated retirement account and should not be attributed to him under Section 16(a).

Why did Michael Castagna of MannKind (MNKD) revoke a prior Form 4?

He revoked the prior Form 4 because it mistakenly showed him directly acquiring 100,000 MannKind shares. The amendment explains those shares were purchased by his spouse in an account where he has no pecuniary interest, so he was not obligated to report the transaction.

Are the 100,000 MannKind (MNKD) shares attributed to Michael Castagna or his spouse?

The 100,000 shares are attributed to Michael Castagna’s spouse, not to him personally. The amendment notes they were acquired in a segregated retirement account in which he has no pecuniary interest, so the transaction is not treated as his beneficial ownership.

Does the amended Form 4 say Michael Castagna had to file under Section 16(a) for MNKD?

The amendment explicitly states Michael Castagna was not obligated to file a Form 4 under Section 16(a) for this transaction. Because he has no pecuniary interest in his spouse’s segregated retirement account, the previously reported acquisition should not be attributed to him.

How many MannKind (MNKD) shares does Michael Castagna directly own after this amendment?

The filing shows Michael Castagna directly owning 2,475,911 MannKind common shares as of March 10, 2026. This figure reflects his reported direct holdings and excludes the 100,000 shares acquired by his spouse in a segregated retirement account.