UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

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. ☐

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

^* The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

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, as amended (the "Exchange Act") or otherwise subject to the liabilities of that section of the Exchange Act but shall be subject to all other provisions of the Exchange Act (however, see the Notes).

CUSIP No.  81663L101

_____________________________

¹ All share amounts presented in this Amendment No. 5 reflect the 33:1 reverse stock split of the Issuer’s Class A Common Stock (as defined below) effective May 4, 2023.

² Based on 27,471,397 shares of Class A Common Stock outstanding as of October 22, 2024, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on October 29, 2024.

CUSIP No.  81663L101

This Amendment No. 5 ("Amendment No. 5") to Schedule 13D relates to the Class A common stock, par value $0.0001 per share (the "Class A Common Stock"), of GeneDX Holdings Corp. (f/k/a Sema4 Holdings Corp.) (the "Issuer"), and amends and supplements the Schedule 13D filed on October 13, 2021 (the "Initial Filing"), as amended by Amendment No. 1, filed on January 21, 2022 ("Amendment No. 1"), Amendment No. 2, filed on May 6, 2022, Amendment No. 3, filed on February 6, 2023, and Amendment No. 4, filed on November 4, 2024 (the Initial Filing, as amended, the "Schedule 13D") by Icahn School of Medicine at Mount Sinai ("ISMMS") and Mount Sinai Health System, Inc. ("MSHS"). As of October 22, 2024, the issued and outstanding Class A Common Stock of the Issuer totaled 27,471,397 shares. The principal executive office of the Issuer is located at 333 Ludlow Street, North Tower, 6th Floor, Stamford, Connecticut 06902.

Item 2 of this Amendment No. 5 incorporates herein by reference the information set forth in Item 2 of the Schedule 13D.

Item 3 of the Schedule 13D is hereby amended and supplemented as follows:

The information set forth in Item 4 of this Amendment No. 5 is hereby incorporated by reference into this Item 3.

Item 4 is hereby amended and supplemented as follows:

On November 15, 2024, ISMMS sold 20,359 shares of Class A Common Stock at a price of $69.7806 per share (before deducting broker commissions), and on November 18, 2024, ISMMS sold 126,782 shares of Class A Common Stock at a price of $70.7755 per share (before deducting broker commissions).  Each sale was made in reliance on Rule 144 promulgated under the Securities Act of 1933. ISMMS previously filed a Form 144 on October 31, 2024, disclosing ISMMS’s intention to sell up to 1,012,941 shares of Class A Common Stock within the next 90 days, which amount includes the aggregate 147,141 shares sold as described above.

The information in Item 3 of the Schedule 13D is incorporated by reference into this Item 4. The Reporting Persons expect to evaluate on an ongoing basis the Issuer's financial condition and prospects and their respective interests in, and intentions with respect to, the Issuer and their respective investments in the securities of the Issuer, which review may be based on various factors, including the Issuer's business and financial condition, results of operations and prospects, general economic and industry conditions, the securities markets in general and those for the Issuer's securities in particular, as well as other developments and other investment opportunities. Accordingly, each Reporting Person reserves the right to change its intentions, as it deems appropriate. In particular, each Reporting Person may, at any time and from time to time, in the open market, in privately negotiated transactions or otherwise, increase its holdings in the Issuer or dispose of all or a portion of the securities of the Issuer that such Reporting Person now owns or may hereafter acquire, including sales pursuant to the exercise of the registration rights provided for in the Subscription Agreements or in the Registration Rights Agreement described in the Schedule 13D, including after the expiration of the lockup as described in Item 6 below.

Except as described in the Schedule 13D, the Reporting Persons do not have any present plans or proposals that relate to or would result in any of the actions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D, although, subject to the agreements described herein, the Reporting Persons, at any time and from time to time, may review, reconsider and change their position and/or change their purpose and/or develop such plans and may seek to influence management or the board of the Issuer with respect to the business and affairs of the Issuer and may from time to time consider pursuing or proposing such matters with advisors, the Issuer or other persons.

 

Item 5 of the Schedule 13D is hereby amended and restated as follows:

The information set forth in Item 4 of this Amendment No. 5 is hereby incorporated by reference into this Item 5.

MSHS disclaims beneficial ownership over all shares beneficially owned by ISMMS, other than for the purpose of determining obligations under the Securities Exchange Act of 1934, as amended, and the filing of this Amendment No. 5 shall not be deemed an admission that MSHS is the beneficial owner of such securities for any other purpose.

Item 6 of the Schedule 13D is hereby amended and restated as follows:

ISMMS had previously reached an understanding with the broker dealer executing the sale that it would not offer, sell, transfer or dispose of any shares of Class A Common Stock, including the 147,141 shares described above, and any additional shares until November 30, 2024, without the consent of the broker dealer. ISMMS has obtained consent from the broker dealer for the sale of the 147,141 shares described above. ISMMS may obtain the consent from the broker dealer to sell additional shares before November 30, 2024, in which case ISMMS does not intend to amend the Schedule 13D again solely due to the receipt of any such consent.

The information set forth in Items 2, 3, 4 and 5 is hereby incorporated by reference into this Item 6. The Subscription Agreements described in Amendment No. 1 provide for certain customary registration rights for the PIPE investors. The Registration Rights Agreement described in the Initial Filing provides for certain customary registration rights for certain shareholders of the Issuer.

Item 7 of this Amendment No. 5 incorporates herein by reference the information set forth in Item 7 of the Schedule 13D.

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.

Dated: November 19, 2024