KYMR (NASDAQ) Form 144 shows large affiliate stock sale activity, including $57.1M trade

Rhea-AI Filing Summary

KYMR notice reports multiple proposed sales of Common Stock by affiliated holders, showing specific sale dates, share quantities, and gross proceeds. The excerpt lists numerous sales by Atlas Venture Fund X, L.P. and related holders, including large transactions on 06/25/2026.

Insights

Securities Compliance Counsel

Form 144 filings notify the market of planned affiliate sales; they are procedural, not consummations.

These entries list proposed dispositions of restricted or control stock by affiliates, including multiple dated rows with share counts and gross proceeds. The filing records specific transactions on 04/15/2026 through 06/25/2026.

Whether sales occur at listed amounts depends on market execution and SEC Rule 144 holding-period and volume limits; subsequent public filings (e.g., Form 4 or broker reports) would confirm final sales and net proceeds.

Key Figures

Largest single proposed sale: 480,992 shares Gross proceeds (largest row): $57,122,898.52 Other large sale example: 243,976 shares +3 more

6 metrics

Largest single proposed sale 480,992 shares sale listed on 06/25/2026 by Atlas Venture Fund X, L.P.

Gross proceeds (largest row) $57,122,898.52 proceeds reported for 480,992 shares on 06/25/2026

Other large sale example 243,976 shares sale listed on 06/22/2026 by Atlas Venture Fund X, L.P.

Proceeds for 06/22/2026 row $24,182,608.35 gross proceeds for 243,976 shares on 06/22/2026

Significant affiliated seller Atlas Venture Fund X, L.P. multiple sale rows between 04/15/2026 and 06/25/2026

Notable individual seller Bruce Booth multiple sales including 11,741 shares on 06/17/2026 for $1,056,443.24

Key Terms

Form 144, restricted securities, affiliate

3 terms

Form 144 regulatory

"144: Securities Sold During The Past 3 Months"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

restricted securities financial

"03/11/2020 | Private Placement | Issuer"

Restricted securities are shares or other investment instruments that come with legal or contractual limits on when and how they can be sold, like stock given to founders or bought in a private offering. Think of them as assets in a locked box that can’t be freely traded until certain conditions — such as a waiting period, company registration, or specific approvals — are met. For investors this matters because restricted securities are less liquid and can affect timing, price, and perceived value when they eventually enter the market.

affiliate regulatory

"Atlas Venture Fund X, L.P. listed as seller"

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Available on EDGAR 06/26/2026 - 04:52 PM Accepted by SEC EDGAR 06/26/2026 - 04:51 PM Learn about SEC filing dates

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 555 California Street 18th Floor San Francisco CA 94104	57451	6690743.46	82257588	06/26/2026	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	03/11/2020	Private Placement	Issuer			57451	03/11/2020	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 Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/15/2026	2750	247765.57
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/22/2026	88	7926.6
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/17/2026	92169	8330667.41
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/18/2026	100928	9185730.49
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/22/2026	243976	24182608.35
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/23/2026	1235	123470.07
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/24/2026	118178	11877944.68
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/25/2026	480992	57122898.52
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/15/2026	385	34687.18
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/22/2026	12	1080.9
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/17/2026	12902	1166143.4
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/18/2026	14128	1285827.52
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/22/2026	34152	3385105.26
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/23/2026	173	17295.81
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/24/2026	16542	1662618.77
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/25/2026	67329	7996032.44
Bruce Booth 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/14/2026	4159	374199.56
Bruce Booth 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/15/2026	2200	197895.00
Bruce Booth 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/22/2026	5900	530746.25
Bruce Booth 300 Technology Sq Ste 8 Cambridge MA 02139	Common	06/17/2026	11741	1056443.24

144: Remarks and Signature

Remarks

Date of Notice

Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1

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 KYMR Form 144 filing mean?

It notifies the SEC and market of proposed affiliate sales of Common Stock by holders such as Atlas Venture. The filing lists dates, share counts, and gross proceeds for proposed transactions between 04/15/2026 and 06/25/2026.

Who are the primary sellers listed in the KYMR excerpt?

The primary sellers shown include Atlas Venture Fund X, L.P., Atlas Venture Opportunity Fund I, L.P., and individual entries for Bruce Booth. Each row shows date, shares sold, and gross proceeds for that transaction.

Do these Form 144 entries confirm completed sales for KYMR?

No, Form 144 provides notice of proposed sales under Rule 144. The excerpt lists proposed sale dates and gross proceeds, but consummation is confirmed only by subsequent transaction records such as broker reports or Form 4 filings.

What is the largest single proposed sale amount in the KYMR excerpt?

The largest single proposed sale listed is 480,992 shares with gross proceeds of $57,122,898.52 on 06/25/2026, as shown in the excerpt rows for Atlas Venture Fund X, L.P.