UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 2)*

COMPASS Pathways plc

(Name of Issuer)

Ordinary Shares**

(Title of Class of Securities)

20451W101**

(CUSIP Number)

Ryan Barrett

ATAI Life Sciences AG

Krausenstraße 9-10,

10117 Berlin, Germany

+49 (0) 89 2153 9035

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

November 29, 2021

(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 Rule 13d-1(e), Rule 13d-1(f) or Rule 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 Rule 13d-7(b) for other parties to whom copies are to be sent.

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

Explanatory Note

This Amendment No. 2 to Schedule 13D amends and supplements the Schedule 13D originally filed with the United States Securities and Exchange Commission (the “SEC”) on May 24, 2021 (as amended, the “Schedule 13D”) relating to the ordinary shares, nominal value £0.008 per ordinary share (the “Ordinary Shares”), of COMPASS Pathways plc, a public limited company under the laws of England and Wales (the “Issuer”). Capitalized terms used herein without definition shall have the meaning set forth in the Schedule 13D.

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

On November 29, 2021 and November 30, 2021, ATAI AG purchased an aggregate 741,000 ADS representing Ordinary Shares for an aggregate purchase price of $23,966,810 in a series of open market transactions. ATAI AG used funds from its working capital for the acquisitions described in this Item 3.

Item 5(a) – (b) of the Schedule 13D is amended and restated in its entirety by inserting the following information:

As of the date of this Schedule 13D, ATAI AG beneficially owns 9,435,758 Ordinary Shares, representing approximately 22.6% of the 41,791,081 Ordinary Shares outstanding as of September 30, 2021. ATAI AG is a wholly owned subsidiary of ATAI NV, and as a result, ATAI NV may be deemed to share beneficial ownership of the Ordinary Shares held by ATAI AG.

Item 5(c) of the Schedule 13D is hereby amended and supplemented as follows:

On November 29, 2021 and November 30, 2021, ATAI AG purchased an aggregate 741,000 ADS representing Ordinary Shares in a series of transactions at an average price of $32.34 per share in a open market transactions on the Nasdaq Global Select Market. Details by date, listing the number of Ordinary Shares acquired and the weighted average price per share are provided below. The Reporting Persons undertake to provide, upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price for these transactions.

Except for the foregoing transactions, since the date of the last amendment to the Schedule 13D neither the Reporting Persons nor any Related Person has effected any transactions in the Ordinary Shares.

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.

Date: December 1, 2021