IRON: 18,039-share Rule 144 notice; prior Atlas Venture exits continue

Rhea-AI Filing Summary

Disc Medicine, Inc. (IRON) notice reports a proposed sale of 18,039 common shares with an aggregate market value of $1,249,741.90, scheduled for 10/07/2025 on Nasdaq. The shares were acquired in a private placement on 05/01/2020 and were paid in cash. The filing shows the issuer has 34,765,581 shares outstanding, so the proposed sale represents a small percentage of total shares. Recent related activity shows multiple secondary sales by affiliated Atlas Venture funds between 07/18/2025 and 08/22/2025, including several large blocks (for example, 53,215 shares sold on 07/23/2025 for $3,244,656.91), indicating ongoing monetization by those funds.

Positive

• Proposed sale size of 18,039 shares is small relative to 34,765,581 shares outstanding
• Shares acquired in 2020 via private placement were paid in cash, simplifying transfer history
• Multiple prior sales by Atlas Venture funds indicate established liquidity and active secondary market exits

Negative

• Significant affiliated selling occurred between 07/18/2025 and 08/22/2025, including a 53,215-share block on 07/23/2025, which may increase supply pressure
• No trading-plan date disclosed in the visible notice, leaving timing rationale and protections unclear

Insights

Equity Capital Markets Analyst

Planned sale is a modest single-holder secondary offering; recent fund sells show continued liquidity.

The proposed sale of 18,039 shares for $1.25M is small relative to the 34.77M shares outstanding, so direct dilution or market impact should be limited if executed as a single block on 10/07/2025. The shares were acquired in a private placement on 05/01/2020, which is a common source for later secondary sales.

Multiple prior disposals by Atlas Venture vehicles between 07/18/2025 and 08/22/2025 — including large lots such as 53,215 shares on 07/23/2025 — indicate ongoing exits by early investors; monitor secondary volumes near 10/07/2025 for short-term liquidity effects on trading spreads.

Corporate Governance Specialist

Insider/affiliate selling is disclosed and follows Rule 144 procedures; representation of no undisclosed material adverse information is included.

The signer certifies absence of undisclosed material adverse information and references Rule 10b5-1 trading-plan language, which can affect timing and legal defensibility of sales. The filing identifies the seller relationship through Atlas Venture funds but does not state any trading-plan adoption date in the visible fields.

Investors should note that documented recent sales by affiliated funds total substantial blocks across multiple dates; confirm future filings for any stated trading-plan dates or additional Form 4/Form 144 notices that would clarify whether sales are pre-planned.

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK
Filer CCC
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer

SEC File Number

Address of Issuer

Phone

Name of Person for Whose Account the Securities are To Be Sold

See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.

Relationship to Issuer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common Stock	Merrill Lynch One Bryant Park New York NY 10036	18039	1249741.9	34765581	10/07/2025	Nasdaq

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common Stock	05/01/2020	Private Placement	Issuer			18039	05/01/2020	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Atlas Venture Opportunity Fund I, LP. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/18/2025	664	40588.79
Atlas Venture Opportunity Fund I, LP. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/23/2025	29837	1819239.47
Atlas Venture Opportunity Fund I, LP. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/24/2025	13033	797188.21
Atlas Venture Opportunity Fund I, LP. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/30/2025	8492	518329.6
Atlas Venture Opportunity Fund I, LP. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/05/2025	395	24075.25
Atlas Venture Opportunity Fund I, LP. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/13/2025	24962	1526501.19
Atlas Venture Opportunity Fund I, LP. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/14/2025	7212	439848.34
Atlas Venture Opportunity Fund I, LP. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/22/2025	2287	139584.07
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/18/2025	1184	72375.2
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/23/2025	53215	3244656.91
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/24/2025	23245	1421824.59
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/30/2025	15146	924472.46
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/05/2025	705	42969.75
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/13/2025	44520	2722531.56
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/14/2025	12862	784432.8
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/22/2025	4080	249017.5

144: Remarks and Signature

Remarks

Date of Notice

ATTENTION:

The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.

Signature

ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)

FAQ

What does the Form 144 for Disc Medicine (IRON) report?

The notice reports a proposed sale of 18,039 common shares valued at $1,249,741.90, to be sold on 10/07/2025 on Nasdaq.

How significant is the proposed sale versus Disc Medicine's outstanding shares (IRON)?

The company has 34,765,581 shares outstanding; the proposed 18,039-share sale represents a very small fraction of total shares outstanding.

When and how were the shares being sold originally acquired?

The shares were acquired in a private placement on 05/01/2020 and payment was made in cash.

Have related parties recently sold IRON shares?

Yes. Atlas Venture funds disclosed multiple sales between 07/18/2025 and 08/22/2025, including 53,215 shares sold on 07/23/2025 for $3,244,656.91.

Does the filing state there is undisclosed adverse information about Disc Medicine (IRON)?

The signer represents they do not know of any material adverse information not publicly disclosed; no contrary facts are listed in the notice.