Avidity Biosciences : February Corporate Presentation

Delivering on the RNA Revolution

February 2021

Forward Looking Statements

We caution the reader that this presentation contains forward-looking statements. All statements other than statements of historical facts contained in this presentation, including statements regarding our future results of operations and financial position, business strategy, the anticipated timing, costs, design and conduct of our ongoing and planned preclinical studies and planned clinical trials, research and development plans, timing and likelihood of success, prospective products, product approvals, plans and objectives of management for future operations, and future results of anticipated product development efforts, are forward-looking statements. In some cases, the reader can identify forward-looking statements by terms such as "may," "will," "should," "expect," "plan," "anticipate," "could,"

"intend," "target," "project," "contemplates," "believes," "estimates," "predicts," "potential" or "continue" or the negative of these terms or other similar expressions. The inclusion of forward-looking statements should not be regarded as a representation by Avidity that any of our plans will be achieved. Actual results may differ from those set forth in this presentation due to the risks and uncertainties inherent in our business, including, without limitation: we are early in our development efforts and all of our development programs are in the preclinical or discovery stage; our approach to the discovery and development of product candidates based on our AOC platform is unproven, and we do not know whether we will be able to develop any products of commercial value; the success of our preclinical studies and clinical trials for our product candidates; the results of preclinical studies and early clinical trials are not necessarily predictive of future results; potential delays in the commencement, enrollment and completion of clinical trials; our dependence on third parties in connection with preclinical testing and product manufacturing; disruption to our operations from the COVID-19 pandemic; unexpected adverse side effects or inadequate efficacy of our product candidates that may limit their development, regulatory approval and/or commercialization, or may result in recalls or product liability claims; regulatory developments in the United States and foreign countries, including acceptance of INDs and similar foreign regulatory filings and our proposed design of future clinical trials; our ability to obtain and maintain intellectual property protection for our product candidates and proprietary technologies; we may use our capital resources sooner than we expect; and other risks described in our filings with the SEC, including under the heading "Risk Factors" in our Prospectus dated June 11, 2020 filed with the SEC on June 12, 2020 and any subsequent filings with the SEC. The reader is cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise. All forward-looking statements are qualified in their entirety by this cautionary statement, which is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

This presentation also contains estimates and other statistical data made by independent parties and by us relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and the reader is cautioned not to give undue weight to such estimates. In addition, projections, assumptions, and estimates of our future performance and the future performance of the markets in which we operate are necessarily subject to a high degree of uncertainty and risk. These and other factors could cause results to differ materially from those expressed in the estimates made by the independent parties and by us.

Utilizing decades of proven science to unlock the power of oligonucleotides

AOCs - A Powerful New Class of Drugs

ANTIBODY OLIGONUCLEOTIDE CONJUGATE (AOC)

OLIGO

• • Combines the proven and safe technologies of monoclonal antibodies and oligonucleotides

  •  Specificity of targeting with mAbs

  •  Potency & precision of oligonucleotides

  •  Targets tissues with potent and durable agents

• • Engineered to deliver to tissues previously untreatable with RNA therapeutics

• • Focused first on muscle, broadening to other tissues (i.e. cardiac) and cell types (i.e. B Cells)

• • Readily scalable with many experienced manufacturers

Delivering on Our Vision

DISRUPTIVE & BROAD	ADVANCING & EXPANDING	AGILE & DIVERSE
PLATFORM	PIPELINE	COMPANY

• • Delivering a New Class of RNA Therapies

• • Demonstrating preclinical proof of concept in multiple tissues

• • Broadening to other tissues & cell types through partnerships & internal discovery

• • Progressing robust pipeline in muscle

• • Entering the clinic with AOC 1001 in 2H 2021

• • Planning for clinical initiations in FSHD & lead DMD program in 2022

• • Leveraging expertise in clinical and commercial execution

• • Assembling an experienced team in rare & RNA therapies

• • Building an integrated and diverse company in service of our patients