United States

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 2)*

Revolution Medicines, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

76155X100

(CUSIP Number)

December 31, 2023

(Date of Event Which Requires Filing 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).

CUSIP No. 76155X100

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CUSIP No. 76155X100

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CUSIP No. 76155X100

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Item 1

700 Saginaw Drive, Redwood City, California 94063, United States of America

Item 2

2(a) Name of Person Filing: BB Biotech AG (“BB Biotech”) on behalf of its wholly-owned subsidiaries, Biotech Growth N.V. (“Biotech Growth”) and Biotech Target N.V. (“Biotech Target”)

BB Biotech AG: Schwertstrasse 6, CH-8200 Schaffhausen, Switzerland

Biotech Growth N.V.: Ara Hill Top Building, Unit A-5, Pletterijweg Oost 1, Curaçao

Biotech Target N.V.: Ara Hill Top Building, Unit A-5, Pletterijweg Oost 1, Curaçao

Biotech Growth N.V.: Curaçao

Biotech Target N.V.: Curaçao

2(e) CUSIP Number: 76155X100

Item 4. Ownership

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

(a) Amount beneficially owned: 5,046,700

(b) Percent of class: 3.1%

(c) Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote 0

(ii) Shared power to vote or to direct the vote 5,046,700

(iii) Sole power to dispose or to direct the disposition of 0

(iv) Shared power to dispose or to direct the disposition of 5,046,700

Item 5. Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following ☒.

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This statement is filed jointly by BB Biotech, Biotech Growth and Biotech Target. Biotech Growth and Biotech Target are wholly-owned subsidiaries of BB Biotech.

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Item 10. Certification

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.

SIGNATURES

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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Exhibit A

Joint Filing Statement

We, the undersigned, hereby express our agreement that the attached Schedule 13G (including all amendments thereto) is filed on behalf of each of the undersigned.

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