COMPASS Pathways : Presentation – January 2023

Transforming Mental Health Care

JANUARY 2023

Disclaimer

Cautionary Note Regarding Forward-LookingStatements This presentation includes "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. In some cases, you can identify forward-looking statements by terms such as "believe," "continue," "could," "estimate," "expect," "may," "might," "plan," "potential," "project," "should," "target," "will," "would," or the negative of these terms, and similar expressions intended to identify forward-looking statements. However, not all forward-looking statements contain these identifying words. These forward-looking statements include express or implied statements relating to our strategic plans or objectives, our plans and expected timing for our phase 3 program in treatment resistant

depression and the potential for that or other trials to support regulatory filings and approvals, our plans and expected timing for our phase 2 trials in anorexia nervosa and post traumatic stress disorder, the future accessibility of COMP360 psilocybin therapy, our ability to launch and successfully commercialize COMP360 psilocybin therapy, potential revenue streams if COMP360 psilocybin therapy is approved and our ability to advance COMP360 psilocybin therapy in other areas of high unmet mental health need and to discover and advance new drug compounds. By their nature, these statements are subject to numerous risk and uncertainties, including the impact of global macroeconomic trends on our business, our expectations about the outcomes of our clinical programs, actions of regulatory agencies, our dependence on third parties in connection with our clinical trials and other factors beyond our control, that could cause our actual results, performance or achievements to differ materially and adversely from those anticipated or implied in our statements. For additional disclosure regarding these and other risks we may face, see the disclosure contained under the heading "Risk Factors" and elsewhere in the Company's most recent Quarterly Report on Form 10-Q and subsequent public filings with the US Securities and Exchange Commission (the "SEC"). You should not rely upon forward-looking statements as predictions of future events. Although our management believes that the expectations reflected in our statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances described in the forward-looking statements will be achieved or occur. Moreover, neither we, nor any other person, assumes responsibility for the accuracy and completeness of these statements. Accordingly, you are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date such statements are made and should not be construed as statements of fact. Except as required by applicable law, we undertake no obligation to update these forward-looking statements to reflect any new information, events or circumstances after the date hereof, or to reflect the occurrence of unanticipated events. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements.

Market & Industry Data Projections, estimates, industry data and information contained in this presentation, including our general expectations about our market position and market opportunity, are based on information from third-party sources, publicly available information, our knowledge of our industry and assumptions based on such information and knowledge. Although we believe that our third party-sources are reliable, we cannot guarantee the accuracy or completeness of our sources. . All of the projections, estimates, market data and industry information used in this presentation involve a number of assumptions and limitations, and you are cautioned not to give undue weight to such information. In addition, projections, estimates and assumptions relating to our and our industry's future performance are necessarily subject to a high degree of uncertainty and risk due to a variety of factors, including, but not limited to, those described above, that could cause future performance to differ materially from our expressed projections, estimates and assumptions or those provided by third parties.

This presentation shall not constitute an offer to sell or the solicitation of an offer to buy securities, nor shall there be any sale of securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

2 | © COMPASS Pathways plc 2023

We're a mental health care company.

We're committed to developing innovative, evidence-based therapies that

help patients and their families, and ease the burden on our overstretched healthcare systems.

3 | © COMPASS Pathways plc 2023

COMP360 psilocybin therapy includes three elements

COMP360 psilocybin therapy

COMP360 psilocybin

Our synthetic, high-purity polymorphic crystalline formulation of psilocybin, a psychoactive compound.

Psychological support

Psychological support from registered and trained mental health professionals.

.

Digital tools

A patient app, therapist portal and AI-driven analytics platform enhancing patient experience and outcomes.

4 | © COMPASS Pathways plc 2023

TRD treatment pathway: significant unmet need for 100 million patients

Treatment pathway stage

Line of therapy

Estimated number of patients (worldwide)

Available treatments

% relapse

New onset depression	Persistent depression	Treatment-resistant depression
Major depressive disorder (MDD)	Major depressive disorder (MDD)	(TRD)
First line		Second line		Third line +
				100 million (~1 in 3 of total)
320 million		200 million	US health care cost approx $17-25k per
				patient/year
			-	Antidepressants
			-	Augmentation therapy
				(antidepressants, mood stabilizers,
	-	Antidepressants		anticonvulsants, atypical antipsychotics,
- Antidepressants	-	Antidepressant combinations		esketamine)
- Psychological interventions, e.g., CBT*	-	Psychological interventions	-	Ketamine
			- Somatic therapy (rTMS, tDCS, ECT,
				DBS)*
			- High-intensity psychological
				interventions
60-70%		50-75%		80-90%

*NOTE: CBT = cognitive behaviorial therapy; rTMS = repetitive transcranial magnetic stimulation; tDCS=transcranial direct current stimulation; ECT=electroconvulsive therapy; DBS=deep brain stimulation

SOURCETable adapted from Rush, A. J., Trivedi, M. H., Wisniewski, S. R., Nierenberg, A. A., Stewart, J. W., Warden, D., ... & Fava, M. (2006). Acute and longer-term outcomes in depressed outpatients requiring one or several treatment steps: a STAR* D report. American Journal of Psychiatry, 163(11), 1905-1917; Zhdanava M, Pilon D, Ghelerter I, et al. The prevalence and national burden of treatment-resistant depression and major depressive disorder in the United

States. J Clin Psychiatry. 2021;82(2):20m13699. 5 | © COMPASS Pathways plc 2023

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