Dianthus Therapeutics (DNTH) director exercises options, sells 599 shares under 10b5-1 plan

Rhea-AI Filing Summary

Dianthus Therapeutics director Paula Soteropoulos reported an exercise-and-sale of 599 shares of common stock. She exercised stock options to acquire 599 shares at $8.44 per share, then sold 599 shares in the open market at $85.47 per share on May 8, 2026.

The stock option related to 599 underlying shares and had an expiration date of June 6, 2032. A footnote states the transaction was carried out under a pre-arranged Rule 10b5-1 trading plan adopted on December 23, 2025, indicating it was scheduled in advance rather than timed discretionarily.

Insider Trade Summary 10b5-1

Net Seller: 599 shares ($51,197)

Net Sell 3 txns

Insider Soteropoulos Paula

Role null

Sold 599 shs ($51K)

Type	Security	Shares	Price	Value
Exercise	Stock Option (Right to Buy)	599	$0.00	--
Exercise	Common Stock	599	$8.44	$5K
Sale	Common Stock	599	$85.47	$51K

Holdings After Transaction: Stock Option (Right to Buy) — 0 shares (Direct, null); Common Stock — 599 shares (Direct, null)

Footnotes (1)

1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 23, 2025. The shares of common stock underlying this stock option award vested as to 25% of the shares on April 6, 2023, with the remaining three quarters vesting in equal monthly installments over the following three years, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

Key Figures

Shares sold: 599 shares Sale price: $85.47/share Options exercised: 599 shares +3 more

6 metrics

Shares sold 599 shares Common Stock sold on May 8, 2026

Sale price $85.47/share Open-market sale price for 599 common shares

Options exercised 599 shares Common shares acquired via option exercise

Option exercise price $8.44/share Conversion or exercise price of stock option

Rule 10b5-1 plan adoption date December 23, 2025 Plan governing the May 8, 2026 transaction

Option expiration June 6, 2032 Expiration date of stock option (right to buy)

Key Terms

Rule 10b5-1 trading plan, Stock Option (Right to Buy), derivative security, open-market sale

4 terms

Rule 10b5-1 trading plan regulatory

"The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 23, 2025."

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.

Stock Option (Right to Buy) financial

"Security title is listed as Stock Option (Right to Buy) for the derivative transaction."

derivative security financial

"The transaction code description notes an Exercise or conversion of derivative security."

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

open-market sale financial

"Transaction action is described as open-market sale for the common stock disposition."

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

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).

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^*

Soteropoulos Paula

(Last) (First) (Middle)

C/O DIANTHUS THERAPEUTICS, INC.

7 TIMES SQUARE, 43RD FLOOR

(Street)

NEW YORK NEW YORK 10036

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Dianthus Therapeutics, Inc. /DE/ [ DNTH ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/08/2026

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	05/08/2026		M(1)		599	A	$8.44	599	D
Common Stock	05/08/2026		S(1)		599	D	$85.47	0	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
Stock Option (Right to Buy)	$8.44	05/08/2026		M(1)			599	(2)	06/06/2032	Common Stock	599	$0	0	D

Explanation of Responses:

1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 23, 2025.

2. The shares of common stock underlying this stock option award vested as to 25% of the shares on April 6, 2023, with the remaining three quarters vesting in equal monthly installments over the following three years, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

	/s/ Adam Veness, as attorney-in-fact for Paula Soteropoulos	05/11/2026
	** 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 did Paula Soteropoulos report in this Form 4 for DNTH?

Paula Soteropoulos reported exercising stock options and selling shares of Dianthus Therapeutics common stock. She exercised options for 599 shares at $8.44 each, then sold 599 shares at $85.47 per share on May 8, 2026 under a Rule 10b5-1 plan.

How many Dianthus Therapeutics (DNTH) shares did the director sell and at what price?

The director sold 599 shares of Dianthus Therapeutics common stock. The sale occurred at an open-market price of $85.47 per share on May 8, 2026, as disclosed in the Form 4 transaction details for the non-derivative common stock entry.

What stock option exercise did the Dianthus Therapeutics director report?

She reported exercising a stock option covering 599 shares of common stock. The option had a conversion or exercise price of $8.44 per share and an expiration date of June 6, 2032, and the exercise was recorded as a derivative security transaction.

Was the Dianthus Therapeutics Form 4 transaction under a Rule 10b5-1 trading plan?

Yes. A footnote states the reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 23, 2025. Such plans pre-schedule trades, indicating the timing of the May 2026 transactions was arranged in advance.

What vesting schedule applied to the Dianthus Therapeutics stock option in this Form 4?

The footnote explains the option’s underlying common shares vested 25% on April 6, 2023. The remaining three quarters then vested in equal monthly installments over the following three years, contingent on the reporting person’s continued service to the company on each vesting date.