UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No.    )*

Merus N.V.

(Name of Issuer)

Common shares, nominal value €0.09 per share

(Title of Class of Securities)

N5749R100

(CUSIP Number)

January 8, 2021

(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)

☒ Rule 13d-1(c)

☐ Rule 13d-1(d)

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).

Merus N.V. (the “Issuer”)

Yalelaan 62

3584 CM Utrecht

The Netherlands

This Schedule 13G is jointly filed by Boxer Capital, LLC (“Boxer Capital”), Boxer Asset Management Inc. (“Boxer Management”), Joe Lewis, MVA Investors, LLC (“MVA Investors”) and Aaron I. Davis (collectively, the “Reporting Persons”). Boxer Management is the managing member and majority owner of Boxer Capital. Joe Lewis is the sole indirect beneficial owner of and controls Boxer Management. MVA Investors is the independent, personal investment vehicle of certain employees of Boxer Capital. Aaron I. Davis is a member of and has voting and dispositive power over securities held by MVA Investors.

The principal business address of Boxer Capital, MVA Investors and Aaron I. Davis is: 12860 El Camino Real, Suite 300, San Diego, CA 92130. The principal business address of Boxer Management and Joe Lewis is: Cay House, EP Taylor Drive N7776, Lyford Cay, New Providence, Bahamas.

Boxer Capital and MVA Investors are limited liability companies organized under the laws of Delaware. Boxer Management is a corporation organized under the laws of the Bahamas. Joe Lewis is a citizen of the United Kingdom. Aaron I. Davis is a citizen of the United States of America.

Common shares, nominal value €0.09 per share (“Common Shares”)

N5749R100

Not applicable.

Boxer Capital, Boxer Management and Joe Lewis beneficially own 1,600,000 Common Shares. MVA Investors and Aaron I. Davis beneficially own 20,000 Common Shares. The Reporting Persons beneficially own, in the aggregate, 1,620,000 Common Shares.

The number of Common Shares beneficially owned by the Reporting Persons in the aggregate represent 5.6% of the Issuer’s outstanding Common Shares (based on 29,088,670 Common Shares outstanding as of October 30, 2020, as set forth in the Issuer’s Form 10-Q filed with the U.S. Securities and Exchange Commission on November 5, 2020).

None of the Reporting Persons has sole power to vote or to direct the vote of any Common Shares.

Boxer Capital, Boxer Management and Joe Lewis have shared power to vote or to direct the vote of the 1,600,000 Common Shares they beneficially own. MVA Investors and Aaron I. Davis have shared power to vote or to direct the vote of the 20,000 Common Shares they beneficially own.

None of the Reporting Persons has sole power to dispose or to direct the disposition of any Common Shares.

Boxer Capital, Boxer Management and Joe Lewis have shared power to dispose or to direct the disposition of the 1,600,000 Common Shares they beneficially own. MVA Investors and Aaron I. Davis have shared power to dispose or to direct the disposition of the 20,000 Common Shares they beneficially own.

Not applicable.

Only Boxer Capital has the right to receive dividends and the proceeds from the sale of the Common Shares held by Boxer Capital. Only MVA Investors has the right to receive dividends and the proceeds from the sale of the Common Shares held by MVA Investors.

Not applicable.

Not applicable.

Not applicable.

(c) By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

Exhibits

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.

January 20, 2021

JOINT FILING AGREEMENT

The undersigned hereby agree that the Statement on Schedule 13G with respect to the common shares of Merus N.V., nominal value €0.09 per share, is, and any amendments thereto executed by each of us shall be, filed on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, and that this Agreement shall be included as an Exhibit to the Schedule 13G and each such amendment. Each of the undersigned agrees to be responsible for the timely filing of the Schedule 13G and any amendments thereto, and for the completeness and accuracy of the information concerning itself contained therein. This Agreement may be executed in any number of counterparts, all of which taken together shall constitute one and the same instrument.

IN WITNESS WHEREOF, the undersigned have executed this Agreement as of January 20, 2021.