Aldeyra Therapeutics : Corporate Overview – May 2021

May 2021

CORPORATE OVERVIEW

Innovative Approaches to Regulating Immune Response

Nasdaq: ALDX

© Aldeyra Therapeutics, Inc. 2021

Disclaimers and Forward-Looking Statements

This presentation and various remarks which may be made during this presentation contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and Section 21E of the Securities Exchange Act of 1934, as amended, including statements regarding Aldeyra's possible or assumed future results of operations, expenses and financing needs, business strategies and plans, research and development plans or expectations, political, economic, legal, social and health risks, including the recent COVID-19 outbreak and subsequent public health measures and other responses to it, that may affect Aldeyra's business or the global economy, the structure, timing and success of Aldeyra's planned or pending clinical trials, expected milestones, market sizing, pricing and reimbursement, competitive position, regulatory matters, industry environment and potential growth opportunities, among other things. The results of earlier preclinical or clinical trials may not be predictive of future results. As a result of the COVID-19 pandemic, clinical site availability, staffing, and patient recruitment

have been negatively affected and the timelines to complete Aldeyra's clinical trials may be delayed. Forward-looking statements include all statements that are not historical facts and, in some cases, can be identified by terms such as "may," "might," "will," "objective," "intend," "should," "could," "can," "would," "expect," "believe," "anticipate," "project," "target," "design," "estimate," "predict," "potential," "plan" or similar expressions and the negatives of those terms.

Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause Aldeyra's actual results, performance or

achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These

statements reflect Aldeyra's current views with respect to future events and are based on assumptions and subject to risks and uncertainties, including the development, clinical and regulatory plans or expectations for Aldeyra's product candidates and systems-based approaches, later developments with the FDA that may be inconsistent with Aldeyra's expectations and beliefs, including the risk that the results from earlier clinical trials or portions of clinical trials may not accurately predict results of subsequent trials or the remainder of a clinical trial for the same or different indications, inconsistent expectations regarding FDA acceptance and review of the company's filings and submitted data sets, and Aldeyra's continuing review and quality control analysis of clinical data. Important

factors that could cause actual results to differ materially from those reflected in Aldeyra's forward-looking statements are described in Aldeyra's most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q, as well as Aldeyra's subsequent filings with the Securities and Exchange Commission. All of Aldeyra's development plans and timelines may be subject to adjustment depending on funding, recruitment rate, regulatory review, preclinical and clinical results, and other

factors any of which could result in changes to Aldeyra's development plans and programs or delay the initiation, completion, or reporting of clinical trials.

In addition to the risks described above and in Aldeyra's other filings with the SEC, other unknown or unpredictable factors also could affect Aldeyra's results. No forward-looking statements can be guaranteed, and actual results may differ materially from such statements. The information in this presentation is provided only as of May 14, 2021, and Aldeyra undertakes no obligation to update any forward-looking statements contained in this presentation on account of new information, future events, or otherwise, except as required by law.

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Compelling Value Proposition

NOVEL SYSTEMS-BASED APPROACHES FOR IMMUNOLOGY

• RASP-inhibitionrepresents a first-in-class therapeutic approach.
• Three unique immune- modulating mechanisms of action in development.

NEAR-TERM DEVELOPMENT CATALYSTS*

• Phase 3 TRANQUILITY and TRANQUILITY-2 results in dry eye disease expected 2H 2021.
• ADX-629Phase 2 clinical testing results in asthma, psoriasis, and COVID-19 expected 2H 2021.

LARGE AND UNDERSERVED MARKET OPPORTUNITY

• Lead product candidate reproxalap targets a U.S. addressable market of >$20B.
• Significant potential commercial advantages of reproxalap in two blockbuster ocular indications.

SOLID CASH POSITION

• Cash, cash equivalents and marketable securities of $138.4M as of 3/31/2021
• Cash runway through the end of 2023, based on projected operating expenses**

*Timing depends, in part, on restrictions related to COVID-19, the availability of clinical research facilities and staffing, the ability to recruit patients, and regulatory feedback.
**Raised $125 million, before deduction of underwriting discounts and commissions and other offering expenses, in gross proceeds in May 2021 underwritten public offering.	3
Runway based on the company's Q1 2021 financial results press release dated May 6, 2021.

Deep and Innovative Pipeline Addressing Immunological Disease

DISEASE AREA	COMPOUND	MECHANISM	INDICATION	PRECLINICAL	PHASE 1	PHASE 2	PHASE 3
Ocular				Dry Eye Disease
Diseases	Reproxalap	RASP
	Allergic Conjunctivitis
				Proliferative Vitreoretinopathy
	ADX-2191	DHFR
	Primary Vitreoretinal Lymphoma
	ADX-103/10X	RASP	Retinal Disease
Systemic				Cytokine Release Syndrome (COVID-19)
Diseases
	ADX-629	RASP	Allergy (Atopic Asthma)
				Autoimmune Disease (Psoriasis)
				Ovarian Cancer			Investigator-Sponsored Trial
	ADX-1612	CHP
		SARS-CoV2 Antiviral (COVID-19)

RASP Mechanism = Reactive Aldehyde Species Inhibitor DHFR Mechanism = Dihydrofolate Reductase Inhibitor CHP Mechanism = Chaperome Inhibitor

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May 2021

REPROXALAP AND ADX-629

Reactive Aldehyde Species (RASP) Inhibition

Nasdaq: ALDX

© Aldeyra Therapeutics, Inc. 2021