KYMR (KYMR) Rule 144: Atlas Venture and Bruce Booth report multi‑date sales

Rhea-AI Filing Summary

KYMR reported multiple Rule 144 notices of proposed sales of Common Stock by affiliated funds and an individual associated with Atlas Venture between April and June 2026. The filings list individual transactions such as 243,976 shares on 06/22/2026 (Atlas Venture Fund X) and 100,928 shares on 06/18/2026 (Atlas Venture Fund X).

The notices present per‑transaction share counts and cash amounts for private placement resale activity and insider/affiliate dispositions; amounts are reported on specific trade dates rather than as an aggregated total.

Insights

Securities Compliance Analyst

Routine Rule 144 resale notices by affiliated holders; disclosure lists dates, share counts, and cash amounts.

The filing lists multiple proposed sales by Atlas Venture Fund X, L.P., Atlas Venture Opportunity Fund I, L.P., and Bruce Booth, with trade dates from 04/14/2026 to 06/23/2026

These items are procedural resale notices under Rule 144 showing per‑transaction shares and proceeds; cash‑flow recipients and any aggregation of totals are not provided in the excerpt.

Key Figures

Sample sale - Atlas Venture Fund X: 243,976 shares Proceeds - Atlas Venture Fund X: $24,182,608.35 Sample sale - Atlas Venture Fund X: 100,928 shares +3 more

6 metrics

Sample sale - Atlas Venture Fund X 243,976 shares sale date 06/22/2026

Proceeds - Atlas Venture Fund X $24,182,608.35 proceeds reported for 243,976 shares on 06/22/2026

Sample sale - Atlas Venture Fund X 100,928 shares sale date 06/18/2026

Proceeds - Atlas Venture Fund X $9,185,730.49 proceeds reported for 100,928 shares on 06/18/2026

Sample sale - Bruce Booth 11,741 shares sale date 06/17/2026

Proceeds - Bruce Booth $1,056,443.24 proceeds reported for 11,741 shares on 06/17/2026

Key Terms

Rule 144, Private Placement, Issuer, Common Stock

4 terms

Rule 144 regulatory

"144: Securities Sold During The Past 3 Months"

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Private Placement financial

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

A private placement is a way for companies to raise money by selling securities directly to a small group of investors instead of through a public offering. This process is often quicker and less regulated, making it similar to offering a special, exclusive investment opportunity to select individuals or institutions. For investors, it can provide access to unique investment options that are not available on public markets.

Issuer regulatory

"Private Placement | Issuer | | | 118178 | 03/11/2020"

Common Stock financial

"Securities To Be Sold 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.

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Available on EDGAR 06/24/2026 - 05:30 PM Accepted by SEC EDGAR 06/24/2026 - 05:30 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	118178	11610988.5	82257588	06/24/2026	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			118178	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 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
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 show?

It lists proposed resale transactions of Common Stock by affiliated holders and an individual. The excerpt shows individual trade dates, share counts and cash amounts for transactions between 04/14/2026 and 06/23/2026.

Who are the primary sellers named in the KYMR excerpt?

Atlas Venture Fund X, Atlas Venture Opportunity Fund I, and Bruce Booth are listed. Each entry includes the seller name, security type (Common), trade date, number of shares and corresponding cash amount.

Are aggregate totals or company proceeds shown in the KYMR excerpt?

No aggregate offering total or issuer proceeds figure is provided in the excerpt. The filing reports per‑transaction share counts and cash amounts on specific dates; aggregate sums are not presented here.

What are examples of large transactions reported in the filing?

Examples include 243,976 shares sold on 06/22/2026 for $24,182,608.35 (Atlas Venture Fund X) and 100,928 shares on 06/18/2026 for $9,185,730.49 (Atlas Venture Fund X).