Keros Therapeutics (KROS) director sells 2,625 shares under Rule 10b5-1 plan

Rhea-AI Filing Summary

Keros Therapeutics director Alpna Seth reported an open-market sale of 2,625 shares of common stock at a weighted average price of $10.72 per share on June 4, 2026. The shares were sold in multiple trades between $10.60 and $10.89. After this transaction, she directly holds 9,767 shares. The sale was made under a pre-arranged Rule 10b5-1 trading plan adopted on December 9, 2025, indicating the timing was planned in advance.

Insider Trade Summary 10b5-1

Net Seller: 2,625 shares ($28,140)

Net Sell 1 txn

Insider Seth Alpna

Role null

Sold 2,625 shs ($28K)

Type	Security	Shares	Price	Value
Sale	Common Stock	2,625	$10.72	$28K

Holdings After Transaction: Common Stock — 9,767 shares (Direct, null)

Footnotes (1)

1. The transactions were pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 9, 2025. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.60 to $10.89 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Key Figures

Shares sold: 2,625 shares Weighted average sale price: $10.72 per share Post-transaction holdings: 9,767 shares +2 more

5 metrics

Shares sold 2,625 shares Open-market sale of common stock

Weighted average sale price $10.72 per share Common stock sale on June 4, 2026

Post-transaction holdings 9,767 shares Shares directly owned after sale

Sale price range $10.60–$10.89 per share Range of individual trade prices

10b5-1 plan adoption date December 9, 2025 Plan governing the reported trades

Key Terms

Rule 10b5-1 trading plan, weighted average price, open-market sale

3 terms

Rule 10b5-1 trading plan regulatory

"The transactions were pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 9, 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.

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

open-market sale financial

"transaction_action: open-market sale"

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.

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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^*

Seth Alpna

(Last) (First) (Middle)

C/O KEROS THERAPEUTICS, INC.

1050 WALTHAM STREET, SUITE 302

(Street)

LEXINGTON MASSACHUSETTS 02421

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Keros Therapeutics, Inc. [ KROS ]

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)
06/04/2026

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	06/04/2026		S(1)		2,625	D	$10.72(2)	9,767	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. The transactions were pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 9, 2025.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.60 to $10.89 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

	/s/ Esther Cho, Attorney-in-Fact	06/08/2026
	** 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 insider transaction did Keros Therapeutics (KROS) disclose for Alpna Seth?

Keros Therapeutics disclosed that director Alpna Seth sold 2,625 shares of common stock in an open-market transaction. The weighted average sale price was $10.72 per share, and the trades occurred within a price range of $10.60 to $10.89.

How many Keros Therapeutics (KROS) shares does Alpna Seth hold after the sale?

After the reported sale, Alpna Seth directly holds 9,767 Keros Therapeutics shares. This figure is disclosed as her post-transaction ownership and helps investors understand that she continues to maintain a meaningful equity stake in the company.

At what prices did Alpna Seth’s Keros Therapeutics (KROS) shares sell?

The reported weighted average sale price was $10.72 per Keros share. Footnotes clarify that individual trades occurred in multiple transactions at prices ranging from $10.60 to $10.89 inclusive during the same trading session.

Was the Keros Therapeutics (KROS) insider sale made under a Rule 10b5-1 plan?

Yes. The filing states that the transactions were executed under a Rule 10b5-1 trading plan adopted by Alpna Seth on December 9, 2025. Such plans pre-schedule trades, reducing the significance of short-term market timing decisions.

What type of insider transaction did Keros Therapeutics (KROS) report for Alpna Seth?

The company reported an open-market sale transaction coded “S” for common stock. This indicates a straightforward disposition of 2,625 shares into the market, rather than an option exercise, tax withholding, gift, or other non-market-related equity movement.