KYMR (KYMR) Form 144 shows Atlas Venture and Bruce Booth proposed sales

Rhea-AI Filing Summary

KYMR submitted Form 144 notices reporting multiple proposed sales of Common Stock by affiliated holders. The excerpt lists several transactions, including Atlas Venture Fund X, L.P.'s proposed sale of 71,814 shares on 03/02/2026 and smaller sales by Atlas Venture Opportunity Fund I and Bruce Booth on 03/02/2026, 04/14/2026, and 04/15/2026.

Key Figures

Atlas Venture Fund X proposed sale: 71,814 shares Atlas Venture Fund X proceeds shown: $6,472,674.74 Atlas Venture Opportunity Fund I proposed sale: 10,052 shares +2 more

5 metrics

Atlas Venture Fund X proposed sale 71,814 shares 03/02/2026

Atlas Venture Fund X proceeds shown $6,472,674.74 03/02/2026 row

Atlas Venture Opportunity Fund I proposed sale 10,052 shares 03/02/2026

Bruce Booth proposed sales (two entries) 4,159 shares; 2,200 shares 04/14/2026 and 04/15/2026

Reported dollar amounts for Bruce Booth rows $374,199.56; $197,895.00 04/14/2026 and 04/15/2026 rows

Key Terms

Form 144, Private Placement, Common Stock

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.

Private Placement financial

"Common Stock | 03/11/2020 | Private Placement"

A private placement is a sale of securities directly to a selected group of investors, typically institutions or accredited investors, instead of through a public offering. It lets a company raise money faster and with fewer regulatory steps; for existing shareholders it matters because the newly issued shares, often sold at a discount, increase the share count and can dilute their ownership.

Common Stock financial

"Common Stock | Merrill Lynch 555 California Street"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 04/22/2026 - 04:52 PM Learn about SEC filing dates

FAQ

What Form 144 transactions does KYMR report?

The filing lists proposed resale notices under Form 144 for Common Stock. It includes Atlas Venture Fund X, Atlas Venture Opportunity Fund I, and individual Bruce Booth with dates of proposed sales on 03/02/2026, 04/14/2026, and 04/15/2026.

How many shares did Atlas Venture Fund X propose to sell for KYMR?

Atlas Venture Fund X, L.P. is shown proposing to sell 71,814 shares on 03/02/2026. The excerpt pairs that share count with a dollar figure of $6,472,674.74, consistent with a reported sale amount in the transaction row.

What sales by Atlas Venture Opportunity Fund I are included?

Atlas Venture Opportunity Fund I, L.P. is listed with a proposed sale of 10,052 shares on 03/02/2026 for $905,997.81 and an additional entry of 385 shares on 04/15/2026 for $34,687.18 in the excerpt.

What transactions involving Bruce Booth appear in the filing?

Bruce Booth is shown with two proposed sales: 4,159 shares on 04/14/2026 for $374,199.56 and 2,200 shares on 04/15/2026 for $197,895.00, as listed in the excerpt's transaction rows.

Are the Form 144 sales listed as private placements or issuer sales?

The excerpt identifies earlier issuances as a Private Placement dated 03/11/2020 and labels the securities as Common Stock with the method shown as Cash. The transaction rows themselves are resale notices on Form 144.

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	12	1056.84	81642394	04/22/2026	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			12	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	03/02/2026	71814	6472674.74
Atlas Venture Fund X, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/15/2026	2750	247765.57
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	03/02/2026	10052	905997.81
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	04/15/2026	385	34687.18
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

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)