Form SCHEDULE 13D/A GeneDx Holdings Corp. Filed by: CMLS Holdings LLC
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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549 |
SCHEDULE 13D
Under the Securities Exchange Act of 1934
(Amendment No. 10)*
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GeneDx Holdings Corp. (Name of Issuer) |
Class A common stock, par value $0.0001 per share (Title of Class of Securities) |
(CUSIP Number) |
Eli Casdin and Keith Meister c/o Corvex Management LP, 667 Madison Avenue New York, NY, 10065 (212) 474-6700 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) |
05/07/2026 (Date of Event Which Requires Filing of This Statement) |
If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.
The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the
Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other
provisions of the Act (however, see the Notes).
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
CMLS HOLDINGS LLC | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
OO | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
537,285.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
1.8 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
C-LSH LLC | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
OO | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
537,285.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
1.8 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
HC, OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
M-LSH LLC | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
OO | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
537,285.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
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| 13 | Percent of class represented by amount in Row (11)
1.8 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
HC, OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Casdin Capital, LLC | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
3,007,164.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
10.1 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IA |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Casdin Partners Master Fund, L.P. | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
WC | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
CAYMAN ISLANDS
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
3,007,164.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
10.1 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Casdin Partners GP, LLC | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
3,026,411.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
10.2 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Eli Casdin | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
UNITED STATES
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
3,599,671.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
12 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IN, HC |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Meister, Keith A. | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
OO | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
UNITED STATES
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
5,005,494.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
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| 13 | Percent of class represented by amount in Row (11)
16.7 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IN, HC |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Corvex Management LP | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
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| 6 | Citizenship or place of organization
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
4,433,297.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
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| 13 | Percent of class represented by amount in Row (11)
14.9 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IA, PN |
SCHEDULE 13D
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| Item 1. | Security and Issuer | |
| (a) | Title of Class of Securities:
Class A common stock, par value $0.0001 per share | |
| (b) | Name of Issuer:
GeneDx Holdings Corp. | |
| (c) | Address of Issuer's Principal Executive Offices:
333 Ludlow Street, North Tower, 6th Floor, Stamford,
CONNECTICUT
, 06902. | |
Item 1 Comment:
This Amendment No. 10 (the "Amendment") supplements the information set forth in the Schedule 13D (the "Schedule 13D") filed with the United States Securities and Exchange Commission (the "SEC") on August 2, 2021, as amended as of January 19, 2022, May 3, 2022, December 5, 2022, February 1, 2023, April 20, 2023, November 17, 2023, May 31, 2024, May 7, 2025, and August 26, 2025 by CMLS Holdings LLC, Keith Meister, Eli Casdin and the other Reporting Persons named therein, relating to the shares of Class A common stock, par value $0.0001 per share ("Shares"), of GeneDx Holdings Corp. (formerly known as Sema4 Holdings Corp., the "Issuer"). Capitalized terms used but not defined herein shall have the meanings ascribed to them in the Schedule 13D, as amended.
The information set forth in response to each separate Item below shall be deemed to be a response to all Items where such information is relevant. Items 3 and 6 to the Schedule 13D are supplementally amended as follows, and Item 5 to the Schedule 13D is amended and restated as follows. Information with respect to each Reporting Person is given solely by such Reporting Person and no Reporting Person assumes responsibility for the accuracy or completeness of the information furnished by another Reporting Person, except as otherwise provided in Rule 13d-1(k). | ||
| Item 3. | Source and Amount of Funds or Other Consideration | |
The information set forth in Item 5(c) is hereby incorporated by reference into this Item 3. Such Shares reported as purchased in Item 5(c) were purchased with the working capital of investment funds advised by Corvex Management LP. The information in the Form 4 filed with the SEC by Keith Meister and Corvex Management LP on March 5, 2026, is incorporated herein by reference. The Shares reported as purchased in such Form 4 were purchased with the working capital of investment funds advised by Corvex Management LP.
Corvex Management LP may effect purchases of securities through margin accounts maintained for investment funds advised by Corvex Management LP with brokers, which extend margin credit as and when required to open or carry positions in their margin accounts, subject to applicable federal margin regulations, stock exchange rules and such firms' credit policies. Positions in Shares may be held in margin accounts and may be pledged as collateral security for the repayment of debit balances in such accounts. | ||
| Item 5. | Interest in Securities of the Issuer | |
| (a) | The information set forth in the facing pages of this Schedule 13D with respect to the sole and shared beneficial ownership and percentage of beneficial ownership of Shares by the Reporting Persons is hereby incorporated by reference into this Item 5. The information in Item 5(b) below is hereby incorporated by reference into this Item 5(a).
References to percentage ownership of Shares in this Statement are based upon the 29,688,027 Shares stated to be outstanding as of May 1, 2026, in the Issuer's Form 10-Q filed with the SEC on May 4, 2026. The filing of this Statement shall not be construed as an admission that a Reporting Person beneficially owns those Shares held by any other Reporting Person. | |
| (b) | Eli Casdin has the sole power to vote or direct the vote and sole power to dispose or to direct the disposition of 35,975 Shares and shared power to vote or to direct the vote and shared power to dispose or to direct the disposition of 3,563,696 Shares. The Shares reflected as beneficially owned by Mr. Casdin include 333,144 Shares and 204,141 Shares issuable upon the exercise of 204,141 private placement warrants of the Issuer. On September 3, 2021, each private placement warrant became exercisable to purchase one Share at a price of $379.50 per share, subject to adjustment, as described in the definitive proxy statement of the Issuer (File No. 001-39482) filed with the SEC on July 2, 2021. CMLS Holdings LLC is the record holder of these Shares and warrants. The Board of Managers of CMLS Holdings LLC is comprised of Mr. Casdin and Mr. Meister who share voting and investment discretion with respect to the Shares held of record by CMLS Holdings LLC. C-LSH LLC and M-LSH LLC are the members of CMLS Holdings LLC, and Mr. Casdin is the managing member of C-LSH LLC. As such, each of the foregoing may be deemed to have or share beneficial ownership of the Shares held directly by CMLS Holdings LLC. Casdin Partners Master Fund, LP is the record holder of 3,007,164 Shares reported herein. Casdin Capital, LLC is the investment adviser to Casdin Partners Master Fund, LP and may be deemed to have or share beneficial ownership of the 3,007,164 Shares held by Casdin Partners Master Fund, LP. Casdin Partners GP, LLC is the general partner of Casdin Partners Master Fund LP and may be deemed to have or share beneficial ownership of the 3,007,164 Shares held by Casdin Partners Master Fund, LP, and Casdin Partners GP, LLC is also the direct beneficial owner of 19,247 Shares. Eli Casdin is the managing member of Casdin Capital, LLC and Casdin Partners GP, LLC. As such, each of the foregoing may be deemed to have or share beneficial ownership of the Shares held directly by Casdin Partners Master Fund, LP and Eli Casdin may be deemed the beneficial owner of the 19,247 Shares held by Casdin Partners GP, LLC. The Shares reflected as solely beneficially owned by Mr. Casdin also include 11,882 Shares issuable upon the exercise of fully vested options, 20,517 Shares that were issued upon the vesting of restricted stock units, and 3,576 Shares to be issued upon vesting of restricted stock units, in each case that were granted to Mr. Casdin in connection with his service on the board of directors of the Issuer.
Keith Meister has the sole power to vote or to direct the vote and sole power to dispose or to direct the disposition of 4,468,209 Shares and shared power to vote or direct the vote and shared power to dispose or to direct the disposition of 537,385 Shares. The Shares reflected as beneficially owned by Mr. Meister include 333,144 Shares and 204,141 Shares issuable upon the exercise of 204,141 private placement warrants of the Issuer. On September 3, 2021, each private placement warrant became exercisable to purchase one Share at a price of $379.50 per share, subject to adjustment, as described in the definitive proxy statement of the Issuer (File No. 001-39482) filed with the SEC on July 2, 2021. CMLS Holdings LLC is the record holder of these Shares and warrants. The Board of Managers of CMLS Holdings LLC is comprised of Mr. Casdin and Mr. Meister who share voting and investment discretion with respect to the Shares held of record by CMLS Holdings LLC. C-LSH LLC and M-LSH LLC are the members of CMLS Holdings LLC, and Mr. Meister is the managing member of M-LSH LLC. As such, each of the foregoing may be deemed to have or share beneficial ownership of the Shares held directly by CMLS Holdings LLC. The Shares reflected as beneficially owned by Mr. Meister include 4,433,297 Shares owned by investment funds advised by Corvex Management LP, which may be deemed to be indirectly beneficially owned by Keith Meister by virtue of Mr. Meister's control of the general partner of Corvex Management LP. The Shares reflected as beneficially owned by Mr. Meister also include 11,207 Shares issuable upon the exercise of fully vested options, 20,129 Shares that were issued upon the vesting of restricted stock units, and 3,576 Shares to be issued upon vesting of restricted stock units within 60 days, in each case that were granted to Mr. Meister in connection with his service on the board of directors of the Issuer. | |
| (c) | The transactions by the Reporting Persons in Shares during the past sixty days are set forth in Exhibit 99.1 and such information is incorporated herein by reference. All such transactions were carried out in open market transactions. | |
| (d) | No person other than the Reporting Persons is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares beneficially owned by the Reporting Persons. | |
| (e) | Not applicable. | |
| Item 6. | Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer | |
Casdin Partners Master Fund, LP entered into cash-settled swaps with Morgan Stanley that represent an aggregate economic long-side exposure comparable to a notional interest in 50,000 Shares (representing economic exposure comparable to approximately 0.2% of the outstanding Shares). The swaps terminate on June 11, 2029, and have a cost basis of $39.6602 per Share. All balances will be settled in cash. In addition, Casdin Partners Master Fund, LP entered into cash-settled swaps with Morgan Stanley that represent an aggregate economic long-side exposure comparable to a notional interest in 300,000 Shares (representing economic exposure comparable to approximately 1.0% of the outstanding Shares). The swaps terminate on June 8, 2029, and have a cost basis of $41.0261 per Share. All balances will be settled in cash. Further, Casdin Partners Master Fund, LP entered into cash-settled swaps with Morgan Stanley that represent an aggregate economic long-side exposure comparable to a notional interest in 500,000 Shares (representing economic exposure comparable to approximately 1.7% of the outstanding Shares). The swaps terminate on June 7, 2029, and have a cost basis of $38.1543 per Share. All balances will be settled in cash. Under the terms of the swaps, the value to be received or paid upon termination of a swap will be determined by the difference in the market price per notional Share on the date of termination as compared to the cost of such notional Share at the time of entry into the swap. The swaps do not give Casdin Partners Master Fund, LP or its control persons direct or indirect voting, investment or dispositive control over any securities of the Issuer and do not require the counterparty thereto to acquire, hold, vote or dispose of any securities of the Issuer. Accordingly, Casdin Partners Master Fund, LP and its control persons disclaim any beneficial ownership of any Shares that may be referenced in the swap contracts or Shares or other securities or financial instruments that may be held from time to time by the counterparty to the contracts. | ||
| Item 7. | Material to be Filed as Exhibits. | |
Exhibit 99.1 Schedule of Transactions in Shares | ||
| SIGNATURE | |
After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
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ATTACHMENTS / EXHIBITS