# EDGAR Filing Document

**Accession Number:** 0001722964
**File Stem:** 0001104659-23-021270
**Filing Date:** 2023-2
**Character Count:** 23944
**Document Hash:** c8ab87439d458d6fe0571285e9757ba3
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-23-021270.hdr.sgml**: 20230214

**ACCESSION NUMBER**: 0001104659-23-021270

**CONFORMED SUBMISSION TYPE**: SC 13G

**PUBLIC DOCUMENT COUNT**: 2

**FILED AS OF DATE**: 20230214

**DATE AS OF CHANGE**: 20230214

**GROUP MEMBERS**: JOHAN WEDELL-WEDELLSBORG

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Y-mAbs Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001722964
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **IRS NUMBER:** 474619612
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SC 13G
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-90649
- **FILM NUMBER:** 23626706

**BUSINESS ADDRESS:**
- **STREET 1:** 230 PARK AVENUE
- **STREET 2:** SUITE 3350
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10169
- **BUSINESS PHONE:** 212-847-9841

**MAIL ADDRESS:**
- **STREET 1:** 230 PARK AVENUE
- **STREET 2:** SUITE 3350
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10169
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** WG Biotech ApS
- **CENTRAL INDEX KEY:** 0001753193
- **IRS NUMBER:** 000000000
- **STATE OF INCORPORATION:** G7
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SC 13G

**BUSINESS ADDRESS:**
- **STREET 1:** RUNGSTED STRANDVEJ 113
- **CITY:** RUNGSTED KYST
- **STATE:** G7
- **ZIP:** 2960
- **BUSINESS PHONE:** 45-45-17-77-77

**MAIL ADDRESS:**
- **STREET 1:** RUNGSTED STRANDVEJ 113
- **CITY:** RUNGSTED KYST
- **STATE:** G7
- **ZIP:** 2960

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, D.C. 20549**

**SCHEDULE 13G**

**Under the Securities Exchange Act of 1934**

**(Amendment No.)\***

**Y-mAbs Therapeutics, Inc.**

(Name of Issuer)

**Common Stock, $0.0001 par value per share**

(Title of Class of Securities)

**984241109**

(CUSIP Number)

**December 31, 2019**

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

◻ Rule 13d-1(b) <br> ◻ Rule 13d-1(c) <br> ⌧ Rule 13d-1(d)

\*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 the disclosures provided in a prior cover page.

The information required in 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).

---

| | | | | |
|:---|:---|:---|:---|:---|
| CUSIP No. 984241109 | CUSIP No. 984241109 | CUSIP No. 984241109 | CUSIP No. 984241109 | CUSIP No. 984241109 |
| &nbsp;&nbsp;&nbsp;&nbsp;1. | &nbsp;&nbsp; Names of Reporting Persons<br> WG Biotech ApS | &nbsp;&nbsp; Names of Reporting Persons<br> WG Biotech ApS | &nbsp;&nbsp; Names of Reporting Persons<br> WG Biotech ApS | &nbsp;&nbsp; Names of Reporting Persons<br> WG Biotech ApS |
| &nbsp;&nbsp;&nbsp;&nbsp;2. | &nbsp;&nbsp;Check the Appropriate Box if a Member of a Group (See Instructions) | &nbsp;&nbsp;Check the Appropriate Box if a Member of a Group (See Instructions) | &nbsp;&nbsp;Check the Appropriate Box if a Member of a Group (See Instructions) | &nbsp;&nbsp;Check the Appropriate Box if a Member of a Group (See Instructions) |
|  | &nbsp;&nbsp; (a)<br> (b) | &nbsp;&nbsp; ◻<br> ◻ | &nbsp;&nbsp; ◻<br> ◻ | &nbsp;&nbsp; ◻<br> ◻ |
| &nbsp;&nbsp;&nbsp;&nbsp;3. | &nbsp;&nbsp;SEC Use Only | &nbsp;&nbsp;SEC Use Only | &nbsp;&nbsp;SEC Use Only | &nbsp;&nbsp;SEC Use Only |
| &nbsp;&nbsp;&nbsp;&nbsp;4. | &nbsp;&nbsp; Citizenship or Place of Organization<br> Denmark | &nbsp;&nbsp; Citizenship or Place of Organization<br> Denmark | &nbsp;&nbsp; Citizenship or Place of Organization<br> Denmark | &nbsp;&nbsp; Citizenship or Place of Organization<br> Denmark |
| Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | 5. | &nbsp;&nbsp; Sole Voting Power<br> 4,178,465 shares |
| Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | 6. | &nbsp;&nbsp; Shared Voting Power<br> 0 |
| Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | 7. | &nbsp;&nbsp; Sole Dispositive Power<br> 4,178,465 shares |
| Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | 8. | &nbsp;&nbsp; Shared Dispositive Power<br> 0 |
| &nbsp;&nbsp;&nbsp;&nbsp;9. | &nbsp;&nbsp; Aggregate Amount Beneficially Owned by Each Reporting Person<br> 4,178,465 shares | &nbsp;&nbsp; Aggregate Amount Beneficially Owned by Each Reporting Person<br> 4,178,465 shares | &nbsp;&nbsp; Aggregate Amount Beneficially Owned by Each Reporting Person<br> 4,178,465 shares | &nbsp;&nbsp; Aggregate Amount Beneficially Owned by Each Reporting Person<br> 4,178,465 shares |
| &nbsp;&nbsp;&nbsp;&nbsp;10. | &nbsp;&nbsp;Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ☐ | &nbsp;&nbsp;Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ☐ | &nbsp;&nbsp;Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ☐ | &nbsp;&nbsp;Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ☐ |
| &nbsp;&nbsp;&nbsp;&nbsp;11. | &nbsp;&nbsp; Percent of Class Represented by Amount in Row (9)<br> 9.6% (1) | &nbsp;&nbsp; Percent of Class Represented by Amount in Row (9)<br> 9.6% (1) | &nbsp;&nbsp; Percent of Class Represented by Amount in Row (9)<br> 9.6% (1) | &nbsp;&nbsp; Percent of Class Represented by Amount in Row (9)<br> 9.6% (1) |
| &nbsp;&nbsp;&nbsp;&nbsp;12. | &nbsp;&nbsp; Type of Reporting Person (See Instructions)<br> OO | &nbsp;&nbsp; Type of Reporting Person (See Instructions)<br> OO | &nbsp;&nbsp; Type of Reporting Person (See Instructions)<br> OO | &nbsp;&nbsp; Type of Reporting Person (See Instructions)<br> OO |

---

(1) The calculation is based on 43,669,509 shares of Common Stock of the Issuer outstanding as of December 31,
2022, as provided by the Issuer.

---

| | | | | |
|:---|:---|:---|:---|:---|
| CUSIP No. 984241109 | CUSIP No. 984241109 | CUSIP No. 984241109 | CUSIP No. 984241109 | CUSIP No. 984241109 |
| &nbsp;&nbsp;&nbsp;&nbsp;1. | &nbsp;&nbsp; Names of Reporting Persons<br> Johan Wedell-Wedellsborg | &nbsp;&nbsp; Names of Reporting Persons<br> Johan Wedell-Wedellsborg | &nbsp;&nbsp; Names of Reporting Persons<br> Johan Wedell-Wedellsborg | &nbsp;&nbsp; Names of Reporting Persons<br> Johan Wedell-Wedellsborg |
| &nbsp;&nbsp;&nbsp;&nbsp;2. | &nbsp;&nbsp;Check the Appropriate Box if a Member of a Group (See Instructions) | &nbsp;&nbsp;Check the Appropriate Box if a Member of a Group (See Instructions) | &nbsp;&nbsp;Check the Appropriate Box if a Member of a Group (See Instructions) | &nbsp;&nbsp;Check the Appropriate Box if a Member of a Group (See Instructions) |
|  | &nbsp;&nbsp; (a)<br> (b) | &nbsp;&nbsp; ◻<br> ◻ | &nbsp;&nbsp; ◻<br> ◻ | &nbsp;&nbsp; ◻<br> ◻ |
| &nbsp;&nbsp;&nbsp;&nbsp;3. | &nbsp;&nbsp;SEC Use Only | &nbsp;&nbsp;SEC Use Only | &nbsp;&nbsp;SEC Use Only | &nbsp;&nbsp;SEC Use Only |
| &nbsp;&nbsp;&nbsp;&nbsp;4. | &nbsp;&nbsp; Citizenship or Place of Organization<br> Denmark | &nbsp;&nbsp; Citizenship or Place of Organization<br> Denmark | &nbsp;&nbsp; Citizenship or Place of Organization<br> Denmark | &nbsp;&nbsp; Citizenship or Place of Organization<br> Denmark |
| Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | 5. | &nbsp;&nbsp; Sole Voting Power<br> 4,305,131 shares (1) |
| Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | 6. | &nbsp;&nbsp; Shared Voting Power<br> 0 |
| Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | 7. | &nbsp;&nbsp; Sole Dispositive Power<br> 4,305,131 shares (1) |
| Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | Number of<br> Shares<br> Beneficially<br> Owned by<br> Each<br> Reporting<br> Person With | 8. | &nbsp;&nbsp; Shared Dispositive Power<br> 0 |
| &nbsp;&nbsp;&nbsp;&nbsp;9. | &nbsp;&nbsp; Aggregate Amount Beneficially Owned by Each Reporting Person<br> 4,305,131 shares (1) | &nbsp;&nbsp; Aggregate Amount Beneficially Owned by Each Reporting Person<br> 4,305,131 shares (1) | &nbsp;&nbsp; Aggregate Amount Beneficially Owned by Each Reporting Person<br> 4,305,131 shares (1) | &nbsp;&nbsp; Aggregate Amount Beneficially Owned by Each Reporting Person<br> 4,305,131 shares (1) |
| &nbsp;&nbsp;&nbsp;&nbsp;10. | &nbsp;&nbsp;Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ☐ | &nbsp;&nbsp;Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ☐ | &nbsp;&nbsp;Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ☐ | &nbsp;&nbsp;Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ☐ |
| &nbsp;&nbsp;&nbsp;&nbsp;11. | &nbsp;&nbsp; Percent of Class Represented by Amount in Row (9)<br> 9.8% (2) | &nbsp;&nbsp; Percent of Class Represented by Amount in Row (9)<br> 9.8% (2) | &nbsp;&nbsp; Percent of Class Represented by Amount in Row (9)<br> 9.8% (2) | &nbsp;&nbsp; Percent of Class Represented by Amount in Row (9)<br> 9.8% (2) |
| &nbsp;&nbsp;&nbsp;&nbsp;12. | &nbsp;&nbsp; Type of Reporting Person (See Instructions)<br> IN | &nbsp;&nbsp; Type of Reporting Person (See Instructions)<br> IN | &nbsp;&nbsp; Type of Reporting Person (See Instructions)<br> IN | &nbsp;&nbsp; Type of Reporting Person (See Instructions)<br> IN |

---

(1) Johan Wedell-Wedellsborg directly owns 126,666 shares of Common Stock issuable to Mr. Wedell-Wedellsborg
upon exercise of stock options exercisable within 60 days after December 31, 2022. In addition, Mr. Wedell-Wedellsborg may be
deemed to beneficially own the 4,178,465 shares of Common Stock directly owned by WG Biotech ApS, of which entity Mr. Wedell-Wedellsborg
is the majority owner.

(2) The calculation is based on dividing (a) the aggregate number of shares of Common Stock with respect
to which Mr. Wedell-Wedellsborg may be deemed to beneficially own as of December 31, 2022, as set forth in Row 9 by (b) the
sum of (i) 43,669,509 shares of Common Stock of the Issuer outstanding as of December 31, 2022, as provided by the Issuer, and
(ii) 126,666 shares of Common Stock issuable to Mr. Wedell-Wedellsborg upon exercise of stock options exercisable within 60
days after December 31, 2022 which are deemed outstanding.

**Explanatory Note**

This Schedule 13G discloses securities beneficially owned by certain Reporting Persons (defined below) as of December 31, 2022 and includes disclosures for which a Schedule 13G and Amendment No. 1 thereto were previously inadvertently not filed by the Reporting Persons as of the years ended December 31, 2019 and 2021, respectively.

---

| | |
|:---|:---|
| **Item 1(a)** | **Name of Issuer:** |

---

Y-mAbs Therapeutics, Inc., a Delaware corporation (the "<u>Issuer</u>")

---

| | |
|:---|:---|
| **Item 1(b)** | **Address of Issuer's principal executive offices:** |

---

230 Park Avenue, Suite 3350

New York, New York 10169

---

| | |
|:---|:---|
| **Items 2(a)** | **Name of Reporting Persons filing:** |

---

This statement is filed by the following reporting persons (collectively referred to as the "<u>Reporting Persons</u>"):

WG Biotech ApS

Johan Wedell-Wedellsborg

---

| | |
|:---|:---|
| **Item 2(b)** | **Address or principal business office or, if none, residence:** |

---

The address of the principal business office of the Reporting Persons is c/o WG Biotech ApS, Rungsted Strandvej 113, Rungsted Kyst, G7, 2960.

---

| | |
|:---|:---|
| **Item 2(c)** | **Citizenship:** |

---

The citizenship of each of the Reporting Persons is Denmark.

---

| | |
|:---|:---|
| **Item 2(d)** | **Title of class of securities:** |

---

Common Stock, $0.0001 par value per share ("<u>Common Stock</u>")

---

| | |
|:---|:---|
| **Item 2(c)** | **CUSIP No.:** |

---

984241109

---

| | |
|:---|:---|
| **Item 3** | **If this statement is filed pursuant to** **§§ 240.13d-1(b), or 240.13d-2(b) or (c), check whether the person filing is a:** |

---

This statement is not filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c).

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| | |
|:---|:---|
| **Item 4** | **Ownership** |

---

The information contained in Rows 5 through 9 and 11 on each of the cover pages of this Schedule 13G is incorporated by reference in its entirety into this Item 4.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(a) Amount beneficially owned:**

As of December 31, 2022, WG Biotech ApS directly held 4,178,465 shares of Common Stock, representing approximately 9.6% of the outstanding shares of Common Stock. This percentage of beneficial ownership is based on 43,669,509 shares of Common Stock of the Issuer outstanding as of December 31, 2022, as provided by the Issuer.

As of December 31, 2022, Mr. Wedell-Wedellsborg directly held 126,666 shares of Common Stock issuable to Mr. Wedell-Wedellsborg upon exercise of stock options exercisable within 60 days after December 31, 2022. In addition, Mr. Wedell-Wedellsborg may be deemed to beneficially own the 4,178,465 shares of Common Stock directly owned by WG Biotech ApS, of which entity Mr. Wedell-Wedellsborg is the majority owner. The aggregate of 4,305,131 shares of Common Stock with respect to which Mr. Wedell-Wedellsborg may be deemed to beneficially own represents approximately 9.8% of the outstanding shares of Common Stock. This percentage of beneficial ownership is based on dividing (a) the aggregate 4,305,131 shares of Common Stock that Mr. Wedell-Wedellsborg may be deemed to beneficially own as of December 31, 2022, by (b) the sum of (i) 43,669,509 shares of Common Stock outstanding as of December 31, 2022, as provided by the Issuer, and (ii) 126,666 shares of Common Stock issuable to Mr. Wedell-Wedellsborg upon exercise of stock options exercisable within 60 days after December 31, 2022 which are deemed outstanding for purposes of this calculation. Mr. Wedell-Wedellsborg disclaims beneficial ownership over the shares held by WG Biotech ApS for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended (the "<u>Act</u>"), and this Schedule 13G shall not be deemed an admission that Mr. Wedell-Wedellsborg is the beneficial owner of such shares for Section 13(d) of the Act or any other purpose.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(b) Percent of Class:**

See responses to Item 11 on each cover page and Item 4(a) above.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(c) Number of shares as to which the Reporting Person has:**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(i) Sole power to vote or to direct the vote:**

See response to Item 5 on each cover page.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(ii) Shared power to vote or to direct the vote:**

See response to Item 6 on each cover page.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(iii) Sole power to dispose or to direct the disposition of:**

See response to Item 7 on each cover page.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(iv) Shared power to dispose or to direct the disposition of:**

See response to Item 8 on each cover page.

A Schedule 13G and Amendment No. 1 thereto were previously inadvertently not filed pursuant to Rule 13d-1(d) under the Act by the Reporting Persons as of the years ended December 31, 2019 and 2021, respectively, as described below.

The Reporting Persons inadvertently failed to file an initial Schedule 13G as of the year ended December 31, 2019. As of December 31, 2019, WG Biotech ApS directly held 5,508,392 shares of Common Stock, representing approximately 13.9% of the outstanding shares of Common Stock on such date. As of December 31, 2019, Mr. Wedell-Wedellsborg directly held 68,444 shares of Common Stock issuable to Mr. Wedell-Wedellsborg upon exercise of stock options exercisable within 60 days after December 31, 2019, and Mr. Wedell-Wedellsborg may have been deemed to beneficially own the 5,508,392 shares of Common Stock directly held by WG Biotech ApS, of which entity Mr. Wedell-Wedellsborg was the majority owner at such time. The aggregate of 5,576,836 shares of Common Stock with respect to which Mr. Wedell-Wedellsborg may have been deemed to beneficially own represented approximately 14.0% of the outstanding shares of Common Stock as of December 31, 2019. This percentage of beneficial ownership is based on dividing (a) the aggregate 5,576,836 shares of Common Stock that Mr. Wedell-Wedellsborg may be deemed to beneficially own as of December 31, 2022, by (b) the sum of (i) 39,728,416 shares of Common Stock outstanding as of December 31, 2019, and (ii) 68,444 shares of Common Stock issuable to Mr. Wedell-Wedellsborg upon exercise of stock options exercisable within 60 days after December 31, 2019 which are deemed outstanding for purposes of this calculation.

The Reporting Persons also inadvertently failed to file an Amendment No. 1 to Schedule 13G as of the year ended December 31, 2021. As of December 31, 2021, WG Biotech ApS directly held 4,178,465 shares of Common Stock, representing approximately 9.6% of the outstanding shares of Common Stock on such date. As of December 31, 2021, Mr. Wedell-Wedellsborg directly held 92,888 shares of Common Stock issuable to Mr. Wedell-Wedellsborg upon exercise of stock options exercisable within 60 days after December 31, 2021, and Mr. Wedell-Wedellsborg may have been deemed to beneficially own the 4,178,465 shares of Common Stock directly held by WG Biotech ApS, of which entity Mr. Wedell-Wedellsborg was the majority owner at such time. The aggregate of 4,271,353 shares of Common Stock with respect to which Mr. Wedell-Wedellsborg may have been deemed to beneficially own represented approximately 9.8% of the outstanding shares of Common Stock as of December 31, 2021. This percentage of beneficial ownership is based on dividing (a) the aggregate 4,271,353 shares of Common Stock that Mr. Wedell-Wedellsborg may be deemed to beneficially own as of December 31, 2022, by (b) sum of (i) 43,694,716 shares of Common Stock outstanding as of December 31, 2021, and (ii) 92,888 shares of Common Stock issuable to Mr. Wedell-Wedellsborg upon exercise of stock options exercisable within 60 days after December 31, 2021 which are deemed outstanding for purposes of this calculation.

---

| | |
|:---|:---|
| **Item 5** | **Ownership of Five Percent or Less of a Class** |

---

Not applicable.

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| | |
|:---|:---|
| **Item 6** | **Ownership of More than Five Percent on Behalf of Another Person** |

---

Not applicable.

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| | |
|:---|:---|
| **Item 7** | **Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person** |

---

Not applicable.

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| | |
|:---|:---|
| **Item 8** | **Identification and Classification of Members of the Group** |

---

Not applicable.

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| | |
|:---|:---|
| **Item 9** | **Notice of Dissolution of Group** |

---

Not applicable.

---

| | |
|:---|:---|
| **Item 10** | **Certifications** |

---

Not applicable.

**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: February 14, 2023

---

| | |
|:---|:---|
| **WG Biotech ApS** | **WG Biotech ApS** |
| By: | /s/ Johan Wedell-Wedellsborg |
| Title: | Chief Executive Officer |
| **Johan Wedell-Wedellsborg** | **Johan Wedell-Wedellsborg** |
| /s/ Johan Wedell-Wedellsborg | /s/ Johan Wedell-Wedellsborg |
| Johan Wedell-Wedellsborg | Johan Wedell-Wedellsborg |

---

**EXHIBIT INDEX**

<u>Exhibit No.</u>

1 Joint Filing Agreement, dated as of February 14, 2023

## Exhibit 99.1

**EXHIBIT 1**

JOINT FILING AGREEMENT

This Joint Filing Agreement (the "<u>Agreement</u>") is made and entered into as of February 14, 2023, by and among WG Biotech ApS and Johan Wedell-Wedellsborg (collectively referred to herein as the "<u>Filers</u>").

Pursuant to and in accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the Filers hereby agree to the joint filing on behalf of each of them all filings on Schedule 13D or Schedule 13G, and any and all amendments thereto and any other document relating thereto (collectively, the "<u>Filings</u>") with respect to the Common Stock, $0.0001 par value per share, of Y-mAbs Therapeutics, Inc., and hereby further agree that this Agreement be included as an exhibit to such statement, as required by such rule. The Filers further agree that they will fully cooperate in the preparation and timely filing (and other delivery) of all such Filings.

IN WITNESS WHEREOF, the Filers hereto have executed this Agreement as of the date first set forth above.

Dated: February 14, 2023

---

| | |
|:---|:---|
| **WG Biotech ApS** | **WG Biotech ApS** |
| By: | /s/ Johan Wedell-Wedellsborg |
| Title: | Chief Executive Officer |
| **Johan Wedell-Wedellsborg** | **Johan Wedell-Wedellsborg** |
| /s/ Johan Wedell-Wedellsborg | /s/ Johan Wedell-Wedellsborg |
| Johan Wedell-Wedellsborg | Johan Wedell-Wedellsborg |

---