Document:

EX-4.5

 Exhibit 4.5 

THIS WARRANT AND THE UNITS ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR
THE SECURITIES LAWS OF ANY STATE AND, EXCEPT AS SET FORTH IN SECTIONS 5.3 AND 5.4 BELOW, MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND LAWS OR, IN THE OPINION OF LEGAL COUNSEL, IN FORM AND
SUBSTANCE SATISFACTORY TO THE ISSUER, SUCH OFFER, SALE, PLEDGE OR OTHER TRANSFER IS EXEMPT FROM SUCH REGISTRATION. 
 WARRANT TO PURCHASE
LIMITED LIABILITY COMPANY COMMON UNITS 
  

			
	Company:	  	AVIDITY BIOSCIENCES LLC, a Delaware limited liability company
	Number of Units:	  	19,918
	Type/Series of Units:	  	Common
	Warrant Price:	  	$0.25 per unit
	Issue Date:	  	June 9, 2017
	Expiration Date:	  	June 9, 2024. See also Section 5.1(b).
	Credit Facility:	  	This Warrant to Purchase Limited Liability Company Common Units (as amended and/or modified and in effect from time to time, the “Warrant”) is issued in connection with the First Amendment to Loan and
Security Agreement dated as of even date herewith between Silicon Valley Bank and the Company, which amends the Loan and Security Agreement dated as of August 7, 2015, between Silicon Valley Bank and the Company (as amended and/or modified and
in effect from time to time, the “Loan Agreement”).

 THIS WARRANT PROVIDES THAT, for good and valuable consideration, SILICON VALLEY BANK (together with any
successor or permitted assignee or transferee of this Warrant or of any units issued upon exercise hereof, “Holder”) is entitled to purchase the number of fully paid and non-assessable
units of limited liability company interest (the “Units”) of the Class (as defined below) of the above-named company (the “Company”) at the above-stated Warrant Price per Unit, all as set forth above
and as adjusted pursuant to Section 2 of this Warrant, subject to the provisions and upon the terms and conditions set forth in this Warrant. Reference is made to Section 5.4 of this Warrant whereby Silicon Valley Bank shall transfer this
Warrant to its parent company, SVB Financial Group. 
 This Warrant shall be exercisable for Common Units (as may be adjusted from time to
time pursuant to the provisions of this Warrant, the “Class”) as further described and defined in, and having the relative rights, powers, preferences and privileges as set forth in, the Company’s Amended and Restated
Operating Agreement dated as of January 31, 2014, as amended and/or restated and in effect from time to time (the “Operating Agreement”). As used herein, “units” refers generally to limited
liability company interests in the Company, whether such interests be styled as units, percentage interests, units or otherwise in the Operating Agreement. 

 SECTION 1.  EXERCISE. 

1.1 Method of Exercise. Holder may at any time and from time to time exercise this Warrant, in whole or in part, by delivering to the
Company the original of this Warrant together with a duly executed Notice of Exercise in substantially the form attached hereto as Appendix 1 and, unless Holder is exercising this Warrant pursuant to a cashless exercise set forth in
Section 1.2, a check, wire transfer of same-day funds (to an account designated by the Company), or other form of payment acceptable to the Company for the aggregate Warrant Price for the Units being
purchased. 
 1.2 Cashless Exercise. On any exercise of this Warrant, in lieu of payment of the aggregate Warrant Price in the manner
as specified in Section 1.1 above, but otherwise in accordance with the requirements of Section 1.1, Holder may elect to receive Units equal to the value of this Warrant, or portion hereof as to which this Warrant is being exercised.
Thereupon, the Company shall issue to the Holder such number of fully paid and non-assessable Units as are computed using the following formula: 

 

			
	X =	  	Y(A-B)/A

 where:

  

			
	X =	  	the number of Units to be issued to the Holder;
		
	Y =	  	the number of Units with respect to which this Warrant is being exercised (inclusive of the Units surrendered to the Company in payment of the aggregate Warrant Price);
		
	A =	  	the Fair Market Value (as determined pursuant to Section 1.3 below) of one Unit; and
		
	B =	  	the Warrant Price.

 1.3 Fair Market Value. If the Company’s common or ordinary units are then traded or quoted
on a nationally recognized securities exchange, inter-dealer quotation system or over-the-counter market (a “Trading Market”) and the
Class is common or ordinary units, the fair market value of a Unit shall be the closing price or last sale price of a common or ordinary unit reported for the Business Day immediately before the date on which Holder delivers this Warrant
together with its Notice of Exercise to the Company. If the Company’s common or ordinary units are then traded in a Trading Market and the Class is a series of convertible preferred units or other units convertible into common or ordinary
units, the fair market value of a Unit shall be the closing price or last sale price of a common or ordinary unit reported for the Business Day immediately before the date on which Holder delivers this Warrant together with its Notice of Exercise to
the Company multiplied by the number of common or ordinary units into which a unit of the Class is then convertible. If the Company’s common or ordinary units are not then traded in a Trading Market, the Manager or Managers of the Company
shall determine the fair market value of a Unit in its, his or their reasonable good faith judgment. 

 1.4 Delivery of Certificate and New Warrant. Within a reasonable time after Holder
exercises this Warrant in the manner set forth in Section 1.1 or 1.2 above, if units of the Class are then certificated by the Company, the Company shall deliver to Holder a certificate representing the Units issued to Holder upon such
exercise and, if this Warrant has not been fully exercised and has not expired, a new warrant of like tenor representing the Units not so acquired. If units of the Class are not then certificated by the Company, the Company will deliver to
Holder such evidence of the issuance of such Units to Holder as required or permitted under the Operating Agreement or, if there be none, such evidence as Holder may reasonably request. 

1.5 Replacement of Warrant. On receipt of evidence reasonably satisfactory to the Company of the loss, theft, destruction or mutilation
of this Warrant and, in the case of loss, theft or destruction, on delivery of an indemnity agreement reasonably satisfactory in form, substance and amount to the Company or, in the case of mutilation, on surrender of this Warrant to the Company for
cancellation, the Company shall, within a reasonable time, execute and deliver to Holder, in lieu of this Warrant, a new warrant of like tenor and amount. 

1.6    Treatment of Warrant Upon Acquisition of Company. 

(a)    Acquisition. For the purpose of this Warrant, “Acquisition” means any transaction or
series of related transactions involving: (i) the sale, lease, exclusive license, or other disposition of all or substantially all of the assets of the Company; (ii) any merger or consolidation of the Company into or with another person or
entity (other than a merger or consolidation effected exclusively to change the Company’s domicile), or any other corporate reorganization, in which the members and other holders of units of the Company in their capacity as such immediately
prior to such merger, consolidation or reorganization, own less than a majority of the Company’s (or the surviving or successor entity’s) outstanding voting power (even if such voting power be limited solely to such matters as required by
applicable law) immediately after such merger, consolidation or reorganization (or, if such Company members and other holders of units beneficially own a majority of the outstanding voting power (even if such voting power be limited solely to such
matters as required by applicable law) of the surviving or successor entity as of immediately after such merger, consolidation or reorganization, such surviving or successor entity is not the Company); or (iii) any sale or other transfer by the
members and/or other holders of units of the Company of units representing at least a majority of the Company’s then-total outstanding combined voting power (even if such voting power be limited solely to such matters as required by applicable
law). 
 (b)    Treatment of Warrant at Acquisition. In the event of an Acquisition in which the consideration to
be received by the Company’s members and other holders of units consists solely of cash, solely of Marketable Securities or a combination of cash and Marketable Securities (a “Cash/Public Acquisition”), and the fair
market value of one Unit as determined in accordance with Section 1.3 above would be greater than the Warrant Price in effect on such date immediately prior to such Cash/Public Acquisition, and Holder has not exercised this Warrant pursuant to
Section 1.1 above as to all Units, then this Warrant shall automatically be deemed to be Cashless Exercised pursuant to Section 1.2 above as to all Units effective immediately prior to and contingent upon the consummation of a Cash/Public
Acquisition. In connection with such Cashless Exercise, Holder shall be deemed to have restated each of the representations and warranties in Section 4 of the Warrant as the date thereof and the Company shall promptly notify the Holder of the
number of Shares (or such other securities) issued upon exercise. In the event of a Cash/Public Acquisition where the fair market value of one Unit as determined in accordance with Section 1.3 above would be less than the Warrant Price in
effect immediately prior to such Cash/Public Acquisition, then this Warrant will expire immediately prior to the consummation of such Cash/Public Acquisition. 

 (c)    Upon the closing of any Acquisition other than a Cash/Public
Acquisition defined above, the acquiring, surviving or successor entity shall assume the obligations of this Warrant, and this Warrant shall thereafter be exercisable for the same securities and/or other property as would have been paid for the
Units issuable upon exercise of the unexercised portion of this Warrant as if such Units were outstanding on and as of the closing of such Acquisition, subject to further adjustment from time to time in accordance with the provisions of this
Warrant. 
 (d)    As used in this Warrant, “Marketable Securities” means securities meeting all
of the following requirements: (i) the issuer thereof is then subject to the reporting requirements of Section 13 or Section 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and is
then current in its filing of all required reports and other information under the Act and the Exchange Act; (ii) the class and series of shares or other security of the issuer that would be received by Holder in connection with the Acquisition
were Holder to exercise this Warrant on or prior to the closing thereof is then traded in Trading Market, and (iii) following the closing of such Acquisition, Holder would not be restricted from publicly
re-selling all of the issuer’s shares and/or other securities that would be received by Holder in such Acquisition were Holder to exercise or convert this Warrant in full on or prior to the closing of
such Acquisition, except to the extent that any such restriction (x) arises solely under federal or state securities laws, rules or regulations, and (y) does not extend beyond six (6) months from the closing of such Acquisition. 

SECTION 2.  ADJUSTMENTS TO THE SHARES AND WARRANT PRICE. 

2.1    Unit Dividends, Splits, Etc. If the Company declares or pays a dividend or distribution on
the outstanding units of the Class payable in additional units of the Class or other units, securities or property (other than cash), then upon exercise of this Warrant, for each Unit acquired, Holder shall receive, without additional cost
to Holder, the total number and kind of units, securities and property which Holder would have received had Holder owned the Units of record as of the date the dividend or distribution occurred. If the Company subdivides the outstanding units of the
Class by reclassification or otherwise into a greater number of units, the number of Units purchasable hereunder shall be proportionately increased and the Warrant Price shall be proportionately decreased. If the outstanding units of the
Class are combined or consolidated, by reclassification or otherwise, into a lesser number of units, the Warrant Price shall be proportionately increased and the number of Units shall be proportionately decreased. 

2.2    Reclassification, Exchange, Combinations or Substitution. Upon any event whereby all of the
outstanding units of the Class are reclassified, exchanged, combined, substituted, or replaced for, into, with or by Company securities of a different class and/or series, then from and after the consummation of such event, this Warrant will be
exercisable for the number, class and series of Company securities that Holder would have received had the Units been outstanding on and as of the consummation of such event, and subject to further adjustment thereafter from time to time in
accordance with the provisions of this Warrant. The provisions of this Section 2.2 shall similarly apply to successive reclassifications, exchanges, combinations substitutions, replacements or other similar events. 

 2.3    Conversion of Convertible Units. If the
Class is a class, type series or other designation of convertible preferred units or other units convertible into common or ordinary units, in the event that all outstanding units of the Class are converted, automatically or by action of
the holders thereof, into common or ordinary units pursuant to the provisions of the Operating Agreement, including, without limitation, in connection with the Company’s initial, underwritten public offering and sale of its units pursuant to an
effective registration statement under the Act (the “IPO”), then from and after the date on which all outstanding units of the Class have been so converted, this Warrant shall be exercisable for such number of common or
ordinary units into which the Units would have been converted had the Units been outstanding on the date of such conversion, and the Warrant Price shall equal the Warrant Price in effect as of immediately prior to such conversion divided by the
number of common or ordinary units into which one Unit would have been converted, all subject to further adjustment thereafter from time to time in accordance with the provisions of this Warrant. 

2.4    Adjustments for Diluting Issuances. Without duplication of any adjustment otherwise provided
for in this Section 2, the number of common or ordinary units issuable upon conversion of the Units shall be subject to anti-dilution adjustment from time to time in the manner set forth in Section 3.03(d)(iv) of the Operating Agreement as
if the Units were issued and outstanding on and as of the date of any such required adjustment. 

2.5    No Fractional Unit. No fractional Unit shall be issuable upon exercise of this Warrant and
the number of Units to be issued shall be rounded down to the nearest whole Unit. If a fractional Unit interest arises upon any exercise of the Warrant, the Company shall eliminate such fractional Unit interest by paying Holder in cash the amount
computed by multiplying the fractional interest by (i) the fair market value (as determined in accordance with Section 1.3 above) of a full Unit, less (ii) the then-effective Warrant Price. 

2.6    Notice/Certificate as to Adjustments. Upon each adjustment of the Warrant Price,
Class and/or number of Units, the Company, at the Company’s expense, shall notify Holder in writing within a reasonable time setting forth the adjustments to the Warrant Price, Class and/or number of Units and facts upon which such
adjustment is based. The Company shall, upon written request from Holder, furnish Holder with a certificate of its Manager, including computations of such adjustment and the Warrant Price, Class and number of Units in effect upon the date of
such adjustment. 
 SECTION 3.  REPRESENTATIONS AND COVENANTS OF THE COMPANY. 

3.1    Representations and Warranties. The Company represents and warrants to, and agrees with, the Holder as
follows: 
 (a)    The initial Warrant Price referenced on the first page of this Warrant is not greater than the fair
market value of a unit of the Class as set forth in the most recently completed 409a valuation report of the Company’s Common Units which valued the Company’s Common Units as of December 31, 2016. 

 (b)    All Units which may be issued upon the exercise of this Warrant,
and all units and/or other securities, if any, issuable upon conversion of the Units, shall, upon issuance, be duly authorized, validly issued, fully paid and non-assessable, and free of any liens and
encumbrances except for restrictions on transfer provided for herein, under the Operating Agreement or under applicable federal and state securities laws. The Company covenants that it shall at all times cause to be reserved and kept available out
of its authorized and unissued units such number of units of the Class, common or ordinary units and other securities as will be sufficient to permit the exercise in full of this Warrant and the conversion of the Units into common or ordinary units
or such other securities, if any. 
 (c)    The Company’s capitalization table attached hereto as Schedule 1 is
true and complete, in all material respects, as of the Issue Date. 
 3.2    Notice of Certain Events. If the
Company proposes at any time to: 
 (a)    declare any dividend or distribution upon the outstanding
units of the Class or, if units of the Class are then convertible into common or ordinary units, such common or ordinary units, whether in cash, property, units, or other securities and whether or not a regular or periodic cash dividend or
distribution (other than a distribution of cash upon the outstanding units of the Class and/or common or ordinary units made solely for the purpose of permitting the holders thereof to satisfy their respective federal and state tax obligations
in respect of the taxable income of the Company); 
 (b)    offer for subscription or sale pro rata to
all holders of the outstanding units of the Class any additional Company units of any type, class, series or other designation (other than pursuant to contractual pre-emptive rights); 

(c)    effect any reclassification, exchange, combination, substitution, reorganization or recapitalization
of the outstanding units of the Class; 
 (d)    effect an Acquisition or to liquidate, dissolve or wind
up; or 
 (e)    effect an IPO; 

then, in connection with each such event, the Company shall give Holder: 

(1)    in the case of the matters referred to in (a) and (b) above, at least seven (7) Business
Days prior written notice of the earlier to occur of the effective date thereof or on which a record will be taken for such dividend, distribution, or subscription rights (and specifying the date on which the holders of outstanding units of the
Class will be entitled thereto) or for determining rights to vote, if any; 
 (2)    in the case of
the matters referred to in (c) and (d) above at least seven (7) Business Days prior written notice of the date when the same will take place (and specifying the date on which the holders of outstanding units of the Class will be
entitled to exchange their units for the securities or other property deliverable upon the occurrence of such event and such reasonable information as Holder may reasonably require regarding the treatment of this Warrant in connection with such
event giving rise to the notice); and 

 (3)    with respect to the IPO, at least seven
(7) Business Days prior written notice of the date on which the Company proposes to file its registration statement in connection therewith. 
 Company
will also provide information requested by Holder that is reasonably necessary to enable Holder to comply with Holder’s accounting or reporting requirements. 

SECTION 4.  REPRESENTATIONS, WARRANTIES OF THE HOLDER. 

The Holder represents and warrants to the Company as follows: 

4.1    Purchase for Own Account. This Warrant and the securities to be acquired upon exercise of
this Warrant by Holder are being acquired for investment for Holder’s account, not as a nominee or agent, and not with a view to the public resale or distribution within the meaning of the Act. Holder also represents that it has not been formed
for the specific purpose of acquiring this Warrant or the Units. 
 4.2    Disclosure of
Information. Holder is aware of the Company’s business affairs and financial condition and has received or has had full access to all the information it considers necessary or appropriate to make an informed investment decision with respect
to the acquisition of this Warrant and its underlying securities. Holder further has had an opportunity to ask questions and receive answers from the Company regarding the terms and conditions of the offering of this Warrant and its underlying
securities and to obtain additional information (to the extent the Company possessed such information or could acquire it without unreasonable effort or expense) necessary to verify any information furnished to Holder or to which Holder has access.

 4.3    Investment Experience. Holder understands that the purchase of this Warrant and its
underlying securities involves substantial risk. Holder has experience as an investor in securities of companies in the development stage and acknowledges that Holder can bear the economic risk of such Holder’s investment in this Warrant and
its underlying securities and has such knowledge and experience in financial or business matters that Holder is capable of evaluating the merits and risks of its investment in this Warrant and its underlying securities and/or has a preexisting
personal or business relationship with the Company and certain of its officers, directors or controlling persons of a nature and duration that enables Holder to be aware of the character, business acumen and financial circumstances of such persons.

 4.4    Accredited Investor Status. Holder is an “accredited investor” within the
meaning of Regulation D promulgated under the Act. 
 4.5    The Act. Holder understands that this
Warrant and the Units issuable upon exercise hereof have not been registered under the Act in reliance upon a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of the Holder’s investment intent
as expressed herein. Holder understands that this Warrant and 

 
the Units issued upon any exercise hereof must be held indefinitely unless subsequently registered under the Act and qualified under applicable state securities laws, or unless exemption from
such registration and qualification are otherwise available. Holder is aware of the provisions of Rule 144 promulgated under the Act. 

4.6    Market Stand-off Agreement. Holder hereby agrees that Holder shall not sell, dispose of,
transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any common units or other securities of Company held by Holder (other than those
included in the registration) during the 180-day period following the effective date of the IPO (or such longer period not to exceed 34 days after the expiration of the
180-day period, as the underwriters or the Company shall request in order to facilitate compliance with NASD Rule 2711 or NYSE Member Rule 472 or any successor or similar rule or regulation) (the
“Market Standoff Provision”); provided, that all officers and managers of the Company and holders of at least one percent (1%) of the Company’s voting securities are bound by and have entered into similar agreements. The Market
Stand-Off Provision may not be amended, modified or waived without the prior written consent of Holder unless such amendment, modification or waiver affects the rights associated with the Units in the same
manner as such amendment, modification or waiver affects the rights associated with all other units of the same series and type as the Units granted pursuant to this Warrant. 

4.7    Rights as Member. Without limiting any provision of this Warrant, Holder agrees that, as a
Holder of this Warrant, it will not have any rights as a member of the Company unless and until the exercise of this Warrant, and then only with respect to the Units issued upon such exercise. Upon exercise of this Warrant, the Company agrees that
Holder shall automatically and without further action by any person be admitted as a member of the Company under the Operating Agreement with respect to the Units issued upon such exercise. 

4.8    No Public Market. Holder understands that no public market now exists for any of the
securities issued by the Company, and that the Company has made no assurances that a public market will ever exist for the securities issuable upon exercise of this Warrant. 

SECTION 5.  MISCELLANEOUS. 

5.1    Term; Automatic Cashless Conversion Upon Expiration. 

(a)    Term. Subject to the provisions of Section 1.6 above, this Warrant is exercisable in whole or in part at any
time and from time to time on or before 6:00 PM, Pacific time, on the Expiration Date and shall be void thereafter. 

(b)    Automatic Cashless Exercise upon Expiration. In the event that, upon the Expiration Date, the fair market
value of one Unit (or other security issuable upon the exercise hereof) as determined in accordance with Section 1.3 above is greater than the Warrant Price in effect on such date, then this Warrant shall automatically be deemed on and as of
such date to be exercised pursuant to Section 1.2 above as to all Units (or such other securities) for which it shall not previously have been exercised, and the Company shall, within a reasonable time, deliver a certificate representing the
Units (or such other securities) issued upon such exercise to Holder. 

 5.2    Legends. Each certificate evidencing
Units, if any (and each certificate evidencing securities issued upon conversion of any Units, if any) shall be imprinted with a legend in substantially the following form: 

THE UNITS EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
“ACT”), OR THE SECURITIES LAWS OF ANY STATE AND, EXCEPT AS SET FORTH IN THAT CERTAIN WARRANT TO PURCHASE LIMITED LIABILITY COMPANY COMMON UNITS ISSUED BY THE ISSUER TO SILICON VALLEY BANK DATED JUNE 9, 2017 MAY NOT BE
OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND LAWS OR, IN THE OPINION OF LEGAL COUNSEL, IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER, SUCH OFFER, SALE, PLEDGE OR OTHER TRANSFER IS EXEMPT FROM SUCH
REGISTRATION. 
 5.3    Compliance with Securities Laws on Transfer. This Warrant and the Units
issuable upon exercise of this Warrant (and the securities issuable, directly or indirectly, upon conversion of the Units, if any) may not be transferred or assigned in whole or in part except in compliance with applicable federal and state
securities laws by the transferor and the transferee (including, without limitation, the delivery of investment representation letters and legal opinions reasonably satisfactory to the Company, as reasonably requested by the Company). The Company
shall not require Holder to provide an opinion of counsel if the transfer is to SVB Financial Group (Silicon Valley Bank’s parent company) or any other affiliate of Holder, provided that any such transferee is an “accredited investor”
as defined in Regulation D promulgated under the Act. Additionally, the Company shall also not require an opinion of counsel if there is no material question as to the availability of Rule 144 promulgated under the Act. 

5.4    Transfer Procedure. After receipt by Silicon Valley Bank of the executed Warrant, Silicon
Valley Bank will transfer all of this Warrant to its parent company, SVB Financial Group. By its acceptance of this Warrant, SVB Financial Group hereby makes to the Company each of the representations and warranties set forth in Section 4
hereof and agrees to be bound by all of the terms and conditions of this Warrant as if the original Holder hereof. Subject to the provisions of Section 5.3 and upon providing the Company with written notice, SVB Financial Group and any
subsequent Holder may transfer all or part of this Warrant or the Units issuable upon exercise of this Warrant (or the securities issuable directly or indirectly, upon conversion of the Units, if any) to any transferee, provided, however, in
connection with any such transfer, SVB Financial Group or any subsequent Holder will give the Company notice of the portion of the Warrant and/or Units (and/or securities issued upon conversion of the Units, if any) being transferred with the name,
address and taxpayer identification number of the transferee and Holder will surrender this Warrant to the Company for reissuance to the transferee(s) (and Holder if applicable); and provided further, that any subsequent transferee other than SVB
Financial Group shall agree in writing with the Company to be bound by all of the terms and conditions of this Warrant; 

 
and provided, further, that any transfer of Units (or of securities issued upon conversion of the Units, if any), shall be subject to the provisions of the Operating Agreement. Notwithstanding
any contrary provision herein, at all times prior to the IPO, Holder may not, without the Company’s prior written consent, transfer this Warrant or any portion hereof, or any Units issued upon any exercise hereof, or any units or other
securities issued upon any conversion of any Units issued upon any exercise hereof, to any person or entity who directly competes with the Company, except in connection with an Acquisition of the Company by such a direct competitor. 

5.5    Notices. All notices and other communications hereunder from the Company to the Holder, or
vice versa, shall be deemed delivered and effective (i) when given personally, (ii) on the third (3rd) Business Day after being mailed by first-class registered or certified mail,
postage prepaid, (iii) upon actual receipt if given by electronic mail and such receipt is confirmed in writing by the recipient, or (iv) on the first Business Day following delivery to a reliable overnight courier service, courier fee
prepaid, in any case at such address as may have been furnished to the Company or Holder, as the case may be, in writing by the Company or such Holder from time to time in accordance with the provisions of this Section 5.5. All notices to
Holder shall be addressed as follows until the Company receives notice of a change of address in connection with a transfer or otherwise: 

SVB Financial Group 

Attn: Treasury Department 

3003 Tasman Drive, HC 215 

Santa Clara, California 95054 

Telephone: 408-654-7400 

Email address: derivatives@svb.com 

Notice to the Company shall be addressed as follows until Holder receives notice of a change in address: 

Avidity Biosciences LLC 

Attn: Troy Wilson 

10975 N. Torrey Pines Road, Suite 150 

La Jolla, California 92037 

With a copy (which shall not constitute notice) to: 

Cooley LLP 

Attn: Joshua Seidenfeld, Esq. 

3175 Hanover Street 

Palo Alto, California 94304 

 5.6    Waiver. This Warrant and any term hereof
may be changed, waived, discharged or terminated (either generally or in a particular instance and either retroactively or prospectively) only by an instrument in writing signed by the party against which enforcement of such change, waiver,
discharge or termination is sought. 
 5.7    Attorney’s Fees. In the event of any dispute
between the parties concerning the terms and provisions of this Warrant, the party prevailing in such dispute shall be entitled to collect from the other party all costs incurred in such dispute, including reasonable attorneys’ fees. 

5.8    Counterparts; Facsimile/Electronic Signatures. This Warrant may be executed in counterparts,
all of which together shall constitute one and the same agreement. Any signature page delivered electronically or by facsimile shall be binding to the same extent as an original signature page with regards to any agreement subject to the terms
hereof or any amendment thereto. 
 5.9    Governing Law. This Warrant shall be governed by and
construed in accordance with the laws of the State of California, without giving effect to its principles regarding conflicts of law. 

5.10    Headings. The headings in this Warrant are for purposes of reference only and shall not
limit or otherwise affect the meaning of any provision of this Warrant. 
 5.11    Business Days.
“Business Day” is any day that is not a Saturday, Sunday or a day on which Silicon Valley Bank is closed. 

[Remainder of page left blank intentionally] 

[Signature page follows] 

 IN WITNESS WHEREOF, the parties have caused this Warrant to Purchase Limited Liability
Company Common Units to be executed by their duly authorized representatives effective as of the Issue Date written above. 
 “COMPANY” 

 

			
	AVIDITY BIOSCIENCES LLC
		
	By:	 	 /s/ Troy Wilson

	Name:	 	Troy Wilson
	Title:	 	President and CEO
	
	“HOLDER”
	
	SILICON VALLEY BANK
		
	By:	 	 /s/ Anthony Flores

	Name:	 	Anthony Flores
	Title:	 	Director

 APPENDIX 1 

NOTICE OF EXERCISE 

1.    The undersigned Holder hereby exercises its right purchase
                     units of the Common Units of AVIDITY BIOSCIENCES LLC (the “Company”) in accordance with the
attached Warrant To Purchase Limited Liability Common Units, and tenders payment of the aggregate Warrant Price for such units as follows: 
  

	 	[    ]	 check in the amount of $             payable
to order of the Company enclosed herewith 

  

	 	[    ]	 Wire transfer of immediately available funds to the Company’s account 

 

	 	[    ]	 Cashless Exercise pursuant to Section 1.2 of the Warrant 

 

	 	[    ]	 Other [Describe]
                                         
                    

2.    If units of the above-stated Class are currently certificated by the Company, please issue a certificate or
certificates representing the Units in the name specified below: 
  

			
		 	      

		
		 	     Holder’s Name

		
		 	      

		
		 	      

		
		 	     (Address)

 3.    By its execution below and for the benefit of the Company, Holder hereby restates
each of the representations and warranties in Section 4 of the Warrant to Purchase Limited Liability Company Common Units as of the date hereof. 
  

			
	
	HOLDER:
	
	      

		
	By:	 	      

		
	Name:	 	      

		
	Title:	 	      

		
	Date:EX-10.1

 Exhibit 10.1 

AMENDED AND RESTATED 

AVIDITY BIOSCIENCES, INC. 

2013 EQUITY INCENTIVE PLAN 

ADOPTED: JANUARY 28, 2013 

APPROVED BY MEMBERS: JANUARY 28, 2013 

AMENDED BY MEMBERS AND MANAGERS: DECEMBER 19, 2016

 AMENDED BY THE BOARD OF DIRECTORS:
NOVEMBER 7, 2019 
 AMENDED BY THE STOCKHOLDERS:
NOVEMBER 7, 2019 
 TERMINATION DATE: JANUARY 27, 2023 

1.    GENERAL. 

(a)    Eligible Award Recipients. Employees, Directors, eligible Consultants and Other
Service Providers of the Company and its Affiliates are eligible to receive Awards. 

(b)    Available Awards. The Plan provides for the grant of Options and Restricted Share
Awards. 
 (c)    Purpose. The Plan, through the granting of Awards, is intended to help
the Company secure and retain the services of eligible Award recipients, provide incentives for such persons to exert maximum efforts for the success of the Company and any Affiliate and provide a means by which the eligible recipients may benefit
from increases in the value of the Shares. 
 2.    ADMINISTRATION. 

(a)    Administration by Board. The Board will administer the Plan. The Board may delegate
administration of the Plan to a Committee or Committees, as provided in Section 2(c). 

(b)    Powers of Board. The Board will have the power, subject to, and within the limitations
of, the express provisions of the Plan: 
 (i)    To determine (A) who will be granted
Awards; (B) when and how each Award will be granted; (C) what type of Award will be granted; (D) the provisions of each Award (which need not be identical), including when a person will be permitted to exercise; (E) the number of
Shares subject to an Award; and (F) the Fair Market Value applicable to an Award. 

 (ii)    To construe and interpret the Plan and
Awards granted under it, and to establish, amend and revoke rules and regulations for administration of the Plan and Awards. The Board, in the exercise of these powers, may correct any defect, omission or inconsistency in the Plan or in any Award
Agreement, in a manner and to the extent it deems necessary or expedient to make the Plan or Award fully effective. 

(iii)    To settle all controversies regarding the Plan and Awards granted under it. 

(iv)    To accelerate, in whole or in part, the time at which an Award may be exercised or vest.

 (v)    To suspend or terminate the Plan at any time. Except as otherwise provided in the Plan
or an Award Agreement, suspension or termination of the Plan will not impair a Participant’s rights under his or her then-outstanding Award without his or her written consent except as provided in subsection (viii) below. 

(vi)    To amend the Plan in any respect the Board deems necessary or advisable, including, without
limitation, by adopting amendments relating to certain nonqualified deferred compensation under Section 409A of the Code and/or to make the Plan or Awards granted under the Plan exempt from or compliant with the requirements for nonqualified
deferred compensation under Section 409A of the Code, subject to the limitations, if any, of applicable law. However, if required by applicable law, and except as provided in Section 10(a) relating to Capitalization Adjustments, no
amendment will be effective unless approved by the Company’s Stockholders if such approval is required by applicable law. Except as provided in the Plan (including subsection (viii) below) or an Award Agreement, no amendment of the Plan
will impair a Participant’s rights under an outstanding Award without his or her written consent. 

(vii)    To submit any amendment to the Plan for stockholder approval. 

(viii)    To approve forms of Award Agreements for use under the Plan and to amend the terms of any
one or more Awards, including, but not limited to, amendments to provide terms more favorable to the Participant than previously provided in the Award Agreement, subject to any specified limits in the Plan that are not subject to Board discretion;
provided however, that, a Participant’s rights under any Award will not be impaired by any such amendment unless (A) the Company requests the consent of the affected Participant, and (B) such Participant consents in writing.
Notwithstanding the foregoing, (1) a Participant’s rights will not be deemed to have been impaired by any such amendment if the Board, in its sole discretion, determines that the amendment, taken as a whole, does not materially impair the
Participant’s rights, and (2) subject to the limitations of applicable law, if any, the Board may amend the terms of any one or more Awards without the affected Participant’s consent to bring the Award into compliance with
Section 409A of the Code or to comply with other applicable laws. 

 (ix)    Generally, to exercise such powers and to
perform such acts as the Board deems necessary or expedient to promote the best interests of the Company and that are not in conflict with the provisions of the Plan or Awards. 

(x)    To adopt such procedures and sub-plans as are
necessary or appropriate to permit participation in the Plan by Employees, Directors, eligible Consultants, and Other Service Providers who are foreign nationals or employed outside the United States (provided that Board approval will not be
necessary for immaterial modifications to the Plan or any Award Agreement that are required for compliance with the laws of the relevant foreign jurisdiction). 

(xi)    To effect, with the consent of any adversely affected Participant, (A) the reduction of
the exercise, purchase or strike price of any outstanding Award; (B) the cancellation of any outstanding Award and the grant in substitution therefore of a new (1) Option, (2) Restricted Share Award, (3) cash and/or (4) other
valuable consideration determined by the Board, in its sole discretion, with any such substituted award (x) covering the same or a different number of Shares as the cancelled Award and (y) granted under the Plan or another equity or
compensatory plan of the Company; or (C) any other action that is treated as a repricing under generally accepted accounting principles. 

(c)    Delegation to Committee. The Board may delegate some or all of the administration of
the Plan to a Committee or Committees. If administration of the Plan is delegated to a Committee, the Committee will have, in connection with the administration of the Plan, the powers theretofore possessed by the Board that have been delegated to
the Committee, including the power to delegate to a subcommittee of the Committee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board will thereafter be to the Committee or
subcommittee). Any delegation of administrative powers will be reflected in resolutions, not inconsistent with the provisions of the Plan, adopted from time to time by the Board or Committee (as applicable). The Committee may, at any time, abolish
the subcommittee and/or revest in the Committee any powers delegated to the subcommittee. The Board may retain the authority to concurrently administer the Plan with the Committee and may, at any time, revest in the Board some or all of the powers
previously delegated. 
 (d)    Delegation to an Officer. The Board may delegate to one or
more Officers the authority to do one or both of the following (i) designate Employees who are not Officers to be recipients of Options (and, to the extent permitted by applicable law, other Awards) and, to the extent permitted by applicable
law, the terms of such Options, and (ii) determine the number of Shares to be subject to such Awards granted to such Employees; provided, however, that the Board resolutions regarding such delegation will specify the total number of
Shares that may be subject to the Awards granted by such Officer and that 

 
such Officer may not grant an Award to himself or herself. Any such Awards will be granted on the form of Award Agreement most recently approved for use by the Committee or the Board, unless
otherwise provided in the resolutions approving the delegation authority. The Board may not delegate authority to an Officer who is acting solely in the capacity of an Officer (and not also as a Director) to determine the Fair Market Value pursuant
to Section 14(u) below. 
 (e)    Effect of Board’s Decision. All determinations,
interpretations and constructions made by the Board in good faith will not be subject to review by any person and will be final, binding and conclusive on all persons. 

3.    SHARES SUBJECT TO THE PLAN. 

(a)    Share Reserve.

(i)    Subject to Section 10(a) relating to Capitalization Adjustments, the aggregate number of
Shares that may be issued pursuant to Awards from and after the Effective Date will not exceed 10,065,722 Shares (the “Share Reserve”). 

(ii)    For clarity, the Share Reserve in this Section 3(a) is a limitation on the number of
Shares that may be issued pursuant to the Plan. Accordingly, this Section 3(a) does not limit the granting of Awards except as provided in Section 8(a). 

(b)    Reversion of Shares to the Share Reserve. If an Award or any portion thereof
(i) expires or otherwise terminates without all of the Shares covered by such Award having been issued, or (ii) is settled in cash (i.e., the Participant receives cash rather than Shares), such expiration, termination or settlement
will not reduce (or otherwise offset) the number of Shares that may be available for issuance under the Plan. If any Shares issued pursuant to an Award are forfeited back to or repurchased by the Company because of the failure to meet a contingency
or condition required to vest such Shares in the Participant, then the Shares that are forfeited or repurchased will revert to and again become available for issuance under the Plan. Any Shares reacquired by the Company in satisfaction of tax
withholding obligations on an Award or as consideration for the exercise or purchase price of an Award will again become available for issuance under the Plan. 

4.    ELIGIBILITY OF CONSULTANTS AND OTHER
SERVICE PROVIDERS. 
 A Consultant or Other Service Provider will not be eligible for the grant of an Award
if, at the time of grant, either the offer or sale of the Company’s securities to such Consultant or Other Service Provider is not exempt under Rule 701 because of the nature of the services that the Consultant or Other Service Provider is
providing to the Company, because the Consultant or Other Service Provider is not a natural person, or because of any other provision of Rule 701, unless the 

 
Company determines that such grant need not comply with the requirements of Rule 701 and will satisfy another exemption under the Securities Act as well as comply with the securities laws of all
other relevant jurisdictions. 
 5.    OPTION TERMS. 

Each Option will be in such form and will contain such terms and conditions as the Board deems appropriate. The provisions of separate Options
need not be identical; provided, however, that each Option Agreement will conform to (through incorporation of provisions hereof by reference in the applicable Option Agreement or otherwise) the substance of each of the following provisions:

 (a)    Term. No Option will be exercisable after the expiration of 10 years from the
date of its grant or such shorter period specified in the Option Agreement. 
 (b)    Exercise
Price. The exercise or strike price of each Option will be not less than 100% of the Fair Market Value of the Shares subject to the Option on the date the Award is granted. Notwithstanding the foregoing, an Option may be granted with an exercise
or strike price lower than 100% of the Fair Market Value of the Shares subject to the Award if such Award is granted pursuant to an assumption of or substitution for another option pursuant to a Company Transaction and in a manner consistent with
the provisions of Section 409A of the Code and, if applicable, Section 424(a) of the Code. 

(c)    Consideration. The purchase price of Shares acquired pursuant to the exercise of an
Option may be paid, to the extent permitted by applicable law and as determined by the Board in its sole discretion, by any combination of the methods of payment set forth below. The Board will have the authority to grant Options that do not permit
all of the following methods of payment (or otherwise restrict the ability to use certain methods) and to grant Options that require the consent of the Company to use a particular method of payment. The permitted methods of payment are as follows:

 (i)    by cash, check, bank draft or money order payable to the Company; 

(ii)    by delivery to the Company (either by actual delivery or attestation) of Shares; 

(iii)    by a “net exercise” arrangement pursuant to which the Company will reduce the
number of Shares issuable upon exercise by the largest whole number of Shares with a Fair Market Value that does not exceed the aggregate exercise price; provided, however, that the Company will accept a cash or other payment from the
Optionholder to the extent of any remaining balance of the aggregate exercise price not satisfied by such reduction in the number of whole Shares to be issued. Shares will no longer be subject to an Option and will not be exercisable thereafter to
the extent that (A) Shares issuable upon exercise are used 

 
to pay the exercise price pursuant to the “net exercise,” (B) Shares are delivered to the Optionholder as a result of such exercise, and (C) Shares are withheld to satisfy tax
withholding obligations;     
 (iv)    according to a deferred payment or
similar arrangement with the Optionholder; provided, however, that interest will compound at least annually and will be charged at the minimum rate of interest necessary to avoid (A) the imputation of interest income to the Company and
compensation income to the Optionholder under any applicable provisions of the Code, and (B) the classification of the Option as a liability for financial accounting purposes; or 

(v)    in any other form of legal consideration that may be acceptable to the Board and is specified
in the applicable Option Agreement. 
 (d)    Transferability. The Board may, in its sole
discretion, impose such limitations on the transferability of Options as the Board will determine. In the absence of such a determination by the Board to the contrary, the following restrictions on the transferability of Options will apply: 

(i)    Restrictions on Transfer. An Option will not be transferable except by will or by the
laws of descent and distribution (or pursuant to subsections (ii) and (iii) below) and will be exercisable during the lifetime of the Optionholder only by the Optionholder. The Board may permit transfer of the Option in a manner that is not
prohibited by applicable tax and securities laws. Except as explicitly provided herein, an Option may not be transferred for consideration. 

(ii)    Domestic Relations Orders. Subject to the approval of the Board or a duly authorized
Officer, an Option may be transferred pursuant to the terms of a domestic relations order, official marital settlement agreement or other divorce or separation instrument.  

(iii)    Beneficiary Designation. Subject to the approval of the Board or a duly
authorized Officer, an Optionholder may, by delivering written notice to the Company, in a form approved by the Company (or the designated broker), designate a third party who, upon the death of the Optionholder, will thereafter be entitled to
exercise the Option and receive the Shares or other consideration resulting from such exercise. In the absence of such a designation, the executor or administrator of the Optionholder’s estate will be entitled to exercise the Option and receive
the Shares or other consideration resulting from such exercise. However, the Company may prohibit designation of a beneficiary at any time, including due to any conclusion by the Company that such designation would be inconsistent with the
provisions of applicable laws. 

 (e)    Vesting Generally. The total number
of Shares subject to an Option may vest and therefore become exercisable in periodic installments that may or may not be equal. The Option may be subject to such other terms and conditions on the time or times when it may or may not be exercised
(which may be based on the satisfaction of performance goals or other criteria) as the Board may deem appropriate. The vesting provisions of individual Options may vary. The provisions of this Section 5(e) are subject to any Option provisions
governing the minimum number of Shares as to which an Option may be exercised. 

(f)    Termination of Continuous Service. Except as otherwise provided in the applicable
Option Agreement or other agreement between the Optionholder and the Company, if an Optionholder’s Continuous Service terminates (other than for Cause and other than upon the Optionholder’s death or Disability), the Optionholder may
exercise his or her Option (to the extent that the Optionholder was entitled to exercise such Option as of the date of termination of Continuous Service) within the period of time ending on the earlier of (i) the date three months following the
termination of the Optionholder’s Continuous Service (or such longer or shorter period specified in the applicable Option Agreement, which period will not be less than 30 days if necessary to comply with applicable laws unless such termination
is for Cause) or (ii) the expiration of the term of the Option as set forth in the Option Agreement. If, after termination of Continuous Service, the Optionholder does not exercise his or her Option within the applicable time frame, the Option
will terminate. 
 (g)    Extension of Termination Date. Except as otherwise provided in
the applicable Option Agreement or other agreement between the Optionholder and the Company, if the exercise of an Option following the termination of the Optionholder’s Continuous Service (other than for Cause and other than upon the
Optionholder’s death or Disability) would be prohibited at any time solely because the issuance of Shares would violate the registration requirements under the Securities Act, then the Option will terminate on the earlier of (i) the
expiration of a total period of three months (that need not be consecutive) after the termination of the Optionholder’s Continuous Service during which the exercise of the Option would not be in violation of such registration requirements, or
(ii) the expiration of the term of the Option as set forth in the applicable Option Agreement. In addition, unless otherwise provided in an Optionholder’s Option Agreement, if the sale of any Shares received upon exercise of an Option
following the termination of the Optionholder’s Continuous Service (other than for Cause) would violate the Company’s insider trading policy, then the Option will terminate on the earlier of (i) the expiration of a period of months
(that need not be consecutive) equal to the applicable post-termination exercise period after the termination of the Optionholder’s Continuous Service during which the sale of Shares received upon exercise of the Option would not be in
violation of the Company’s insider trading policy, or (ii) the expiration of the term of the Option as set forth in the applicable Option Agreement. 

(h)    Disability of Optionholder. Except as otherwise provided in the applicable Option
Agreement or other agreement between the Optionholder and the Company, if an Optionholder’s Continuous Service terminates as a result of the Optionholder’s Disability, the Optionholder may exercise his or her Option (to the extent that the
Optionholder was 

 
entitled to exercise such Option as of the date of termination of Continuous Service), but only within such period of time ending on the earlier of (i) the date 12 months following such
termination of Continuous Service (or such longer or shorter period specified in the Option Agreement, which period will not be less than 6 months if necessary to comply with applicable laws), and (ii) the expiration of the term of the Option
as set forth in the Option Agreement. If, after termination of Continuous Service, the Optionholder does not exercise his or her Option within the applicable time frame, the Option will terminate. 

(i)    Death of Optionholder. Except as otherwise provided in the applicable Option Agreement
or other agreement between the Optionholder and the Company, if (i) an Optionholder’s Continuous Service terminates as a result of the Optionholder’s death, or (ii) the Optionholder dies within the period (if any) specified in
the Option Agreement for exercisability after the termination of the Optionholder’s Continuous Service (for a reason other than death), then the Option may be exercised (to the extent the Optionholder was entitled to exercise such Option as of
the date of death) by the Optionholder’s estate, by a person who acquired the right to exercise the Option by bequest or inheritance or by a person designated to exercise the Option upon the Optionholder’s death, but only within the period
ending on the earlier of (i) the date 18 months following the date of death (or such longer or shorter period specified in the Option Agreement, which period will not be less than 6 months if necessary to comply with applicable laws), and
(ii) the expiration of the term of such Option as set forth in the Option Agreement. If, after the Optionholder’s death, the Option is not exercised within the applicable time frame, the Option will terminate. 

(j)    Termination for Cause. Except as explicitly provided otherwise in an
Optionholder’s Option Agreement, if an Optionholder’s Continuous Service is terminated for Cause, the Option will terminate immediately upon such Optionholder’s termination of Continuous Service, and the Optionholder will be
prohibited from exercising his or her Option from and after the time of such termination of Continuous Service.  

(k)    Non-Exempt Employees. If an Option is granted
to an Employee who is a nonexempt employee for purposes of the Fair Labor Standards Act of 1938, as amended, the Option will not be first exercisable for any Shares until at least six months following the date of grant of the Option (although the
Option may vest prior to such date). Consistent with the provisions of the Worker Economic Opportunity Act, the vested portion of any Options may be exercised earlier than six months following the date of grant (i) if such non-exempt Employee dies or suffers a Disability, (ii) upon a Company Transaction in which such Option is not assumed, continued or substituted, (iii) upon a Change in Control, or (iv) upon
Optionholder’s retirement (as such term may be defined in the Optionholder’s Option Agreement, in another agreement between the Optionholder and the Company, or, if no such definition is provided for, in accordance with the Company’s
then current employment policies and guidelines). The foregoing provision is intended to operate so that any income derived by a non-exempt employee in connection with the exercise or vesting of an Option will
be exempt from his or her regular rate of pay. To the extent permitted and/or required for compliance with the Worker Economic Opportunity Act to 

 
ensure that any income derived by a non-exempt Employee in connection with the exercise, vesting or issuance of any Shares under any other Award will be
exempt from the employee’s regular rate of pay, the provisions of this Section 5(k) will apply to all Awards and are hereby incorporated by reference into such Award Agreements.  

(l)    Early Exercise of Options. An Option may, but need not, include a provision whereby
the Optionholder may elect at any time before the Optionholder’s Continuous Service terminates to exercise the Option as to any part or all of the Shares subject to the Option prior to the full vesting of the Option. Subject to the Repurchase
Limitation in Section 9(k), any unvested Shares so purchased may be subject to a repurchase right in favor of the Company or to any other restriction the Board determines to be appropriate. Provided that the Repurchase Limitation in
Section 9(k) is not violated, the Company will not be required to exercise its repurchase right until at least six months (or such longer or shorter period of time required to avoid classification of the Option as a liability for financial
accounting purposes) have elapsed following exercise of the Option unless the Board specifically provides otherwise in the Option Agreement. 

(m)    Right of Repurchase. Subject to the Repurchase Limitation in Section 9(k), the
Option may include a provision whereby the Company may elect to repurchase all or any part of the vested Shares acquired by the Optionholder pursuant to the exercise of the Option. 

(n)    Right of First Refusal. The Option may include a provision whereby the Company may
elect to exercise a right of first refusal following receipt of notice from the Optionholder of the intent to transfer all or any part of the Shares received upon the exercise of the Option. Such right of first refusal will be subject to the
Repurchase Limitation in Section 9(k). Except as expressly provided in this Section 5(n) or in the Option Agreement, such right of first refusal will otherwise comply with any applicable provisions of the Stockholder Documents. 

6.    RESERVED. 

7.    RESTRICTED SHARE AWARD TERMS. 

Each Restricted Share Award Agreement will be in such form and will contain such terms and conditions as the Board deems appropriate. At the
Board’s election, Shares may be (i) held in book entry form subject to the Company’s instructions until any restrictions relating to the Restricted Share Award lapse; or (ii) evidenced by a certificate, which certificate will be
held in such form and manner as determined by the Board. The terms and conditions of Restricted Share Award Agreements may change from time to time, and the terms and conditions of separate Restricted Share Award Agreements need not be identical.
Each Restricted Share Award Agreement will conform to (through incorporation of the provisions hereof by reference in the agreement or otherwise) the substance of each of the following provisions:  

 (i)    Consideration. A Restricted Share
Award may be awarded in consideration for (A) cash, check, bank draft or money order payable to the Company, (B) past services to the Company or an Affiliate, or (C) any other form of legal consideration (including future
services) that may be acceptable to the Board, in its sole discretion, and permissible under applicable law. 

(ii)    Vesting. Subject to the “Repurchase Limitation” in Section 9(k),
Shares awarded under the Restricted Share Award Agreement may be subject to forfeiture to the Company in accordance with a vesting schedule to be determined by the Board. 

(iii)    Termination of Participant’s Continuous Service. If a Participant’s
Continuous Service terminates, the Company may receive through a forfeiture condition or a repurchase right, any or all of the Shares held by the Participant as of the date of termination of Continuous Service under the terms of the Restricted Share
Award Agreement. 
 (iv)    Transferability. Rights to acquire Shares under the Restricted
Share Award Agreement will be transferable by the Participant only upon such terms and conditions as are set forth in the Restricted Share Award Agreement, as the Board will determine in its sole discretion, so long as Shares awarded under the
Restricted Share Award Agreement remain subject to the terms of the Restricted Share Award Agreement. 

(v)    Right of First Refusal. The Restricted Share Award may include a provision whereby the
Company may elect to exercise a right of first refusal following receipt of notice from the Participant of the intent to transfer all or any part of the Shares received pursuant to the Restricted Share Award Agreement. Except as expressly provided
in this Section 7(iv), or in the Restricted Share Award Agreement, such right of first refusal will otherwise comply with any applicable provisions of the Stockholder Documents. 

8.    COVENANTS OF THE COMPANY. 

(a)    Availability of Shares. The Company will keep available at all times the number of
Shares reasonably required to satisfy then-outstanding Awards.  
 (b)    Securities Law
Compliance. The Company will seek to obtain from each regulatory commission or agency having jurisdiction over the Plan such authority as may be required to grant Awards and to issue Shares upon exercise of the Options; provided, however,
that this undertaking will not require the Company to register under the Securities Act the Plan, any Award or any Shares issued or issuable pursuant to any such Award. If, after reasonable efforts and at a reasonable cost, the Company is unable to
obtain from any such regulatory commission or agency the authority that counsel for the Company deems 

 
necessary for the lawful issuance of Shares under the Plan, the Company will be relieved from any liability for failure to issue Shares upon exercise of such Options or vesting of such Profits
Interest unless and until such authority is obtained. A Participant will not be eligible for the grant of an Award or the subsequent issuance of Shares pursuant to the Award if such grant or issuance would be in violation of any applicable
securities law.     
 (c)    No Obligation to Notify or Minimize Taxes.
The Company will have no duty or obligation to any Optionholder to advise such holder as to the time or manner of exercising such Option. Furthermore, the Company will have no duty or obligation to warn or otherwise advise such holder of a
pending termination or expiration of an Option or a possible period in which the Option may not be exercised. The Company has no duty or obligation to minimize the tax consequences of an Award to the holder of such Award. 

9.    MISCELLANEOUS. 

(a)    Use of Proceeds from Sales of Shares. Proceeds from the sale of Shares pursuant to
Awards will constitute general funds of the Company. 
 (b)    Company Action Constituting
Grant of Awards. Company action constituting a grant by the Company of an Award to any Participant will be deemed completed as of the date of such company action, unless otherwise determined by the Board, regardless of when the instrument,
certificate, or letter evidencing the Award is communicated to, or actually received or accepted by, the Participant. If the company records (e.g., Board consents, resolutions or minutes) documenting the company action approving the Award contains
terms (e.g., exercise price, vesting schedule or number of Shares) that are inconsistent with those in the Award Agreement as a result of a clerical error in papering the Award Agreement, the company records will control and the Participant will
have no legally binding right to the incorrect term in the Award Agreement. 

(c)    Shareholder Rights. No Participant will be deemed to be the holder of, or to have any
of the rights of a holder with respect to, any Shares subject to such Award unless and until (i) such Participant has satisfied all requirements for exercise of, or the issuance of Shares under, the Award pursuant to its terms, and
(ii) the issuance of the Shares subject to such Award has been entered into the books and records of the Company. A Participant to whom a Share is issued in accordance with the Plan will have such rights with respect to such Share as are
provided in the applicable Stockholder Documents. 
 (d)    No Employment or Other Service
Rights. Nothing in the Plan, any Award Agreement or any other instrument executed thereunder or in connection with any Award granted pursuant thereto will confer upon any Participant any right to continue to serve the Company or an Affiliate in
the capacity in effect at the time the Award was granted or will affect the right of the Company or an Affiliate to terminate (i) the employment of an Employee with or without notice and with or without cause, (ii) the service of a
Consultant or Other Service Provider pursuant to the terms of such Consultant’s or Other Service Provider’s agreement with the Company or an Affiliate, or (iii) the service of a Director pursuant to the LLC Agreement, and any
applicable provisions of the law of the state in which the Company or the Affiliate is organized, as the case may be. 

 (e)    Change in Time Commitment. If a
Participant’s regular level of time commitment in the performance of his or her services for the Company and any Affiliates is reduced for any reason (for example, and without limitation, if the Participant is an Employee of the Company and the
Employee has a change in status from a full-time Employee to a part-time Employee) after the date of grant of any Award to the Participant, the Board has the right in its sole discretion to (x) make a corresponding reduction in the number of
Shares subject to any portion of such Award that are scheduled to vest or become payable after the date of such change in time commitment, and (y) in lieu of or in combination with such a reduction, extend the vesting or payment schedule
applicable to such Award. In the event of any such reduction, the Participant will have no right with respect to any portion of the Award that is so reduced. 

(f)    Investment Assurances; Execution of Stockholder Documents. The Company may require a
Participant, as a condition of exercising or acquiring Shares under any Award, to (i) give written assurances satisfactory to the Company as to the Participant’s knowledge and experience in financial and business matters and/or to employ a
purchaser representative reasonably satisfactory to the Company who is knowledgeable and experienced in financial and business matters and that he or she is capable of evaluating, alone or together with the purchaser representative, the merits and
risks of exercising the Award; (ii) give written assurances satisfactory to the Company stating that the Participant is acquiring Shares subject to the Award for the Participant’s own account and not with any present intention of selling
or otherwise distributing the Shares; and (iii) execute any applicable Stockholder Documents. The foregoing requirements, and any assurances given pursuant to such requirements, will be inoperative if (A) the issuance of the Shares upon
the exercise or acquisition of Shares under the Award has been registered under a then currently effective registration statement under the Securities Act, or (B) as to any particular requirement, a determination is made by counsel for the
Company that such requirement need not be met in the circumstances under the then applicable securities laws. The Company may, upon advice of counsel to the Company, place legends on certificates issued under the Plan (if any) as such counsel deems
necessary or appropriate in order to comply with applicable securities laws, including, but not limited to, legends restricting the transfer of the Shares. 

(g)    Withholding Obligations. Unless prohibited by the terms of an Award Agreement, the
Company may, in its sole discretion, satisfy any federal, state or local tax withholding obligation relating to an Award by any of the following means (in addition to the Company’s right to withhold from any compensation paid to the Participant
by the Company) or by a combination of such means: (i) requiring the Participant to tender a cash payment; (ii) withholding Shares from the Shares issued or otherwise issuable to the Participant in connection with the Award; provided,
however, that no Shares are withheld with a value exceeding the minimum amount of tax required to be withheld by law (or such lesser amount as may be necessary to avoid classification of the Award as a liability for

 
financial accounting purposes); (iii) withholding cash from an Award settled in cash; (iv) withholding payment from any amounts otherwise payable to the Participant; or (v) by such
other method as may be set forth in the Award Agreement.     

(h)    Electronic Delivery. Any reference herein to a “written” agreement or
document will include any agreement or document delivered electronically or posted on the Company’s intranet (or other shared electronic medium controlled by the Company to which the Participant has access). 

(i)    Deferrals. To the extent permitted by applicable law, the Board, in its sole
discretion, may determine that the delivery of Shares or the payment of cash, upon the exercise, vesting or settlement of all or a portion of any Award may be deferred and may establish programs and procedures for deferral elections to be made by
Participants. Deferrals by Participants will be made in accordance with Section 409A of the Code. Consistent with Section 409A of the Code, the Board may provide for distributions while a Participant is still an employee or otherwise
providing services to the Company. The Board is authorized to make deferrals of Awards and determine when, and in what annual percentages, Participants may receive payments, including lump sum payments, following the Participant’s termination
of Continuous Service, and implement such other terms and conditions consistent with the provisions of the Plan and in accordance with applicable law. 

(j)    Compliance with Section 409A. To the extent that the Board
determines that any Award granted hereunder is subject to Section 409A of the Code, the Award Agreement evidencing such Award will incorporate the terms and conditions necessary to avoid the consequences specified in Section 409A(a)(1) of
the Code. To the extent applicable, the Plan and Award Agreements will be interpreted in accordance with Section 409A of the Code. 

(k)    Repurchase Limitation. The terms of any repurchase right will be specified in the
Award Agreement. The repurchase price for vested Shares will be the Fair Market Value of the Shares on the date of repurchase. The repurchase price for unvested Shares will be the lower of (i) the Fair Market Value of the Shares on the date of
repurchase or (ii) the original purchase price paid. However, the Company will not exercise its repurchase right until at least six months (or such longer or shorter period of time as may be necessary to avoid classification of the Award as a
liability for financial accounting purposes) have elapsed following delivery of Shares subject to the Award, unless otherwise specifically provided by the Board. 

10.    ADJUSTMENTS UPON CHANGES IN CAPITALIZATION;
OTHER COMPANY EVENTS. 
 (a)    Capitalization
Adjustments. In the event of a Capitalization Adjustment, the Board will appropriately and proportionately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), and (ii) the
class(es) and number of securities and price per Share subject to outstanding Awards. The Board will make such adjustments, and its determination will be final, binding and conclusive.     

 (b)    Dissolution or Liquidation. Except
as otherwise provided in the Award Agreement, in the event of a dissolution or liquidation of the Company, all outstanding Awards (other than Awards consisting of vested and outstanding Shares not subject to a forfeiture condition or the
Company’s right of repurchase) will terminate immediately prior to the completion of such dissolution or liquidation, and the Shares subject to the Company’s repurchase rights or subject to a forfeiture condition may be repurchased or
reacquired by the Company notwithstanding the fact that the holder of such Award is providing Continuous Service, provided, however, that the Board may, in its sole discretion, cause some or all Awards to become fully vested, exercisable
and/or no longer subject to repurchase or forfeiture (to the extent such Awards have not previously expired or terminated) before the dissolution or liquidation is completed but contingent on its completion. 

(c)    Company Transaction. The following provisions will apply to Awards in the event of a
Company Transaction unless otherwise provided in the instrument evidencing the Award or any other written agreement between the Company or any Affiliate and the Participant or unless otherwise expressly provided by the Board at the time of grant of
an Award. In the event of a Company Transaction, then, notwithstanding any other provision of the Plan, the Board may take one or more of the following actions with respect to Awards, contingent upon the closing or completion of the Company
Transaction: 
 (i)    arrange for the surviving Entity or acquiring Entity (or the surviving or
acquiring Entity’s parent company) to assume or continue the Award or to substitute a similar award for the Award (including, but not limited to, an award to acquire the same consideration paid to the Company’s Stockholders of the Company
pursuant to the Company Transaction); 
 (ii)    arrange for the assignment of any reacquisition
or repurchase rights held by the Company in respect of Shares issued pursuant to the Award to the surviving Entity or acquiring Entity (or the surviving or acquiring Entity’s parent company); 

(iii)    accelerate the vesting, in whole or in part, of the Award (and, if applicable, the time at
which the Award may be exercised) to a date prior to the effective time of such Company Transaction as the Board may determine (or, if the Board does not determine such a date, to the date that is five days prior to the effective date of the Company
Transaction), with such Award terminating if not exercised (if applicable) at or prior to the effective time of the Company Transaction; provided, however, that the Board may require Participants to complete and deliver to the Company a
notice of exercise before the effective date of a Company Transaction, which exercise is contingent upon the effectiveness of such Company Transaction; 

 (iv)    arrange for the lapse, in whole or in
part, of any reacquisition or repurchase rights held by the Company with respect to the Award; 

(v)    cancel or arrange for the cancellation of the Award, to the extent not vested or not
exercised prior to the effective time of the Company Transaction, in exchange for such cash consideration, if any, as the Board, in its sole discretion, may consider appropriate; and 

(vi)    make a payment, in such form as may be determined by the Board equal to the excess, if any,
of (A) the value of the property the Participant would have received upon the exercise of the Award immediately prior to the effective time of the Company Transaction, over (B) any exercise price payable by such holder in connection with
such exercise. For clarity, this payment may be $0 if the value of the property is equal to or less than the exercise price. Payments under this provision may be delayed to the same extent that payment of consideration to the holders of the
Company’s Shares in connection with the Company Transaction is delayed as a result of escrows, earn outs, holdbacks or any other contingencies. The Board need not take the same action or actions with respect to all Awards or portions thereof or
with respect to all Participants. The Board may take different actions with respect to the vested and unvested portions of an Award.  

(d)    Change in Control. An Award may be subject to additional acceleration of vesting and
exercisability upon or after a Change in Control as may be provided and defined in the Award Agreement or grant notice for such Award or as may be provided in any other written agreement between the Company or any Affiliate and the Participant, but
in the absence of such provision, no such acceleration will occur. 
 11.    TERMINATION OR
SUSPENSION OF THE PLAN. 

(a)    Plan Term. The Board may suspend or terminate the Plan at any time. Unless terminated
sooner by the Board, the Plan will automatically terminate on the day before the 10th anniversary of the earlier of (i) the date the Plan is adopted by the Board, or (ii) the date the
Plan is approved by the Company’s Stockholders. No Awards may be granted under the Plan while the Plan is suspended or after it is terminated. 

(b)    No Impairment of Rights. Suspension or termination of the Plan will not impair rights
and obligations under any Award granted while the Plan is in effect except with the written consent of the affected Participant or as otherwise permitted in the Plan. 

 12.    EFFECTIVE DATE OF
PLAN. 
 This Plan will become effective on the Effective Date. 

13.    CHOICE OF LAW. 

The law of the State of California will govern all questions concerning the construction, validity and interpretation of this Plan, without
regard to that state’s conflict of laws rules. 
 14.    DEFINITIONS. As used in the Plan, the
following definitions will apply to the capitalized terms indicated below:  

(a)    “Affiliate” means, at the time of determination, any
“parent” or “majority-owned subsidiary” of the Company, as such terms are defined in Rule 405. The Board will have the authority to determine the time or times at which “parent” or “majority-owned subsidiary”
status is determined within the foregoing definition. 
 (b)    “Award
Agreement” means a written agreement between the Company and a Participant evidencing the terms and conditions of an Award grant. Each Award Agreement will be subject to the terms and conditions of the Plan.  

(c)    “Award” means any right to receive Shares granted under the Plan,
including an Option or a Profits Interest.  

(d)    “Board” means the Board of Directors of the
Company.  
 (e)    “Capitalization Adjustment” means any
change that is made in, or other events that occur with respect to, the Shares subject to the Plan or subject to any Award after the Effective Date without the receipt of consideration by the Company (through merger, consolidation, reorganization,
recapitalization, incorporation, change in state of organization, distribution (whether in property or cash), equity split, reverse equity split, liquidating distribution, combination of Shares, exchange of Shares, change in form of organization or
structure, or any similar equity restructuring transaction, as that term is used in Statement of Financial Accounting Standards Board Accounting Standards Codification Topic 718 (or any successor thereto). Notwithstanding the foregoing, the
conversion of any convertible securities of the Company will not be treated as a Capitalization Adjustment. 

(f)    “Cause” will have the meaning ascribed to such term in any written
agreement between the Participant and the Company defining such term and, in the absence of such agreement, such term means, with respect to a Participant, the occurrence of any of the following events: (i) such Participant’s
commission of any felony or any crime involving fraud, dishonesty or moral turpitude under the laws of the United States or any state thereof; (ii) such Participant’s attempted commission of, or participation in, a fraud or act of
dishonesty against the Company; (iii) such Participant’s intentional, material violation of any contract or agreement between the Participant and the Company or of any statutory duty owed to the Company; (iv) such Participant’s
unauthorized use or disclosure 

 
of the Company’s confidential information or trade secrets; or (v) such Participant’s gross misconduct. The determination that a termination of the Participant’s Continuous
Service is either for Cause or without Cause will be made by the Company, in its sole discretion. Any determination by the Company that the Continuous Service of a Participant was terminated with or without Cause for the purposes of outstanding
Awards held by such Participant will have no effect upon any determination of the rights or obligations of the Company or such Participant for any other purpose.  

(g)    “Change in Control” means the occurrence in a single transaction or
in a series of related transactions, of any one or more of the following events: 
 (i)    any
Exchange Act Person becomes the Owner, directly or indirectly, of securities of the Company representing more than 50% of the combined voting power of the Company’s then outstanding securities other than by virtue of a merger, consolidation or
similar transaction. Notwithstanding the foregoing, a Change in Control will not be deemed to occur (A) on account of the acquisition of securities of the Company directly from the Company, (B) on account of the acquisition of securities
of the Company by an investor, any affiliate thereof or any other Exchange Act Person that acquires the Company’s securities in a transaction or series of related transactions the primary purpose of which is to obtain financing for the Company
through the issuance of equity securities or (C) solely because the level of Ownership held by any Exchange Act Person (the “Subject Person”) exceeds the designated percentage threshold of the outstanding voting
securities as a result of a repurchase or other acquisition of voting securities by the Company reducing the number of Shares outstanding, provided that if a Change in Control would occur (but for the operation of this sentence) as a result of the
acquisition of voting securities by the Company, and after such Share acquisition, the Subject Person becomes the Owner of any additional voting securities that, assuming the repurchase or other acquisition had not occurred, increases the percentage
of the then outstanding voting securities Owned by the Subject Person over the designated percentage threshold, then a Change in Control will be deemed to occur; 

(ii)    there is consummated a merger, consolidation or similar transaction involving (directly or
indirectly) the Company and, immediately after the consummation of such merger, consolidation or similar transaction, the Company’s Stockholders of the Company immediately prior thereto do not Own, directly or indirectly, either
(A) outstanding voting securities representing more than 50% of the combined outstanding voting power of the surviving Entity in such merger, consolidation or similar transaction or (B) more 50% of the combined outstanding voting power of
the parent of the surviving Entity in such merger, consolidation or similar transaction, in each case in substantially the same proportions as their Ownership of the outstanding voting securities of the Company immediately prior to such transaction;

 (iii)    there is consummated a sale, lease,
exclusive license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries, other than a sale, lease, license or other disposition of all or substantially all of the consolidated assets of the
Company and its Subsidiaries to an Entity, more than 50% of the combined voting power of the voting securities of which are Owned by Company’s Stockholders of the Company in substantially the same proportions as their Ownership of the
outstanding voting securities of the Company immediately prior to such sale, lease, license or other disposition; or 

(iv)    individuals who, on the date the Plan is adopted by the Board, are Company’s
Stockholders of the Board (the “Incumbent Board”) cease for any reason to constitute at least a majority of the Company’s Stockholders of the Board; provided, however, that if the appointment or election (or
nomination for election) of any new Board member was approved or recommended by a majority vote of the Company’s Stockholders of the Incumbent Board then still in office, such new member will, for purposes of this Plan, be considered as a
member of the Incumbent Board.  
 Notwithstanding the foregoing definition or any other provision of this Plan, (A) the term Change in Control
will not include a sale of assets, merger or other transaction effected exclusively for the purpose of changing the domicile of the Company, and (B) the definition of Change in Control (or any analogous term) in an individual written agreement
between the Company or any Affiliate and the Participant will supersede the foregoing definition with respect to Awards subject to such agreement; provided, however, that if no definition of Change in Control or any analogous term is set
forth in such an individual written agreement, the foregoing definition will apply. 
 To the extent required for compliance with Section 409A of the
Code, in no event will a Change in Control be deemed to have occurred if such transaction is not also a “change in the ownership or effective control of” the Company or “a change in the ownership of a substantial portion of the assets
of” the Company as determined under Treasury Regulations Section 1.409A-3(i)(5) (without regard to any alternative definition thereunder). The Board may, in its sole discretion and without a
Participant’s consent, amend the definition of “Change in Control” to conform to the definition of “Change in Control” under Section 409A of the Code, and the regulations thereunder. 

(h)    “Code” means the Internal Revenue Code of 1986, as amended, including
any applicable regulations and guidance thereunder. 
 (i)    “Committee”
means a committee of one or more Directors to whom authority has been delegated by the Board in accordance with Section 2(c). 

 (j)    “Company Transaction”
means the consummation, in a single transaction or in a series of related transactions, of any one or more of the following events: 

(i)    a sale, lease or other disposition of all or substantially all, as determined by the Board in
its sole discretion, of the consolidated assets of the Company and its Subsidiaries; 
 (ii)    a
sale or other disposition of at least 90% of the outstanding securities of the Company; 

(iii)    a merger, consolidation, or similar transaction following which the Company is not the
surviving Entity; 
 (iv)    a merger, consolidation or similar transaction following which the
Company is the surviving Entity but the Shares outstanding immediately preceding the merger, consolidation or similar transaction are converted or exchanged by virtue of the merger consolidation or similar transaction into other property, whether in
the form of securities, cash or otherwise. To the extent required for compliance with Section 409A of the Code, in no event will an event be deemed a Company Transaction if such transaction is not also a “change in the ownership or
effective control of” the Company or “a change in the ownership of a substantial portion of the assets of” the Company as determined under Treasury Regulation Section 1.409A-3(i)(5)
(without regard to any alternative definition thereunder). 

(k)    “Company” means Avidity Biosciences, Inc., a Delaware corporation.

 (l)    “Consultant” means any person, including an advisor, who is
(i) engaged by the Company or an Affiliate to render consulting or advisory services and is compensated for such services, or (ii) serving as a member of the board of directors or directors of an Affiliate and is compensated for such
services. However, the term “Consultant” will not include Company’s Stockholders, and service solely as a Director, or payment of a fee for such service, will not cause a Director to be considered a “Consultant” for purposes
of the Plan. 
 (m)    “Continuous Service” means that the
Participant’s service with the Company or an Affiliate, whether as an Employee, Consultant or Director, is not interrupted or terminated. A change in the capacity in which the Participant renders service to the Company or an Affiliate as an
Employee, Consultant or Director or a change in the Entity for which the Participant renders such service, provided that there is no interruption or termination of the Participant’s service with the Company or an Affiliate, will not terminate a
Participant’s Continuous Service; provided, however, that if the Entity for which a Participant is rendering services ceases to qualify as an Affiliate, as determined by the Board in its sole discretion, such Participant’s
Continuous Service will be considered to have terminated on the date such Entity ceases to qualify as an Affiliate. For example, a change in status from an Employee of the Company to a Consultant of an Affiliate or to

 
a Director will not constitute an interruption of Continuous Service. To the extent permitted by law, the Board or an officer of the Company designated by the Board, in that party’s sole
discretion, may determine whether Continuous Service will be considered interrupted in the case of (i) any leave of absence approved by that party, including sick leave, military leave or any other personal leave, or (ii) transfers between
the Company, an Affiliate, or their successors. Notwithstanding the foregoing, a leave of absence will be treated as Continuous Service for purposes of vesting in an Award only to such extent as may be provided in the Company’s leave of absence
policy, in the written terms of any leave of absence agreement or policy applicable to the Participant, or as otherwise required by law. 

(n)    “Director” means a member of the Board. 

(o)    “Disability” means, with respect to a Participant, the
inability of such Participant to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment that can be expected to result in death or that has lasted or can be expected to last for a continuous
period of not less than 12 months as provided in Sections 22(e)(3) and 409A(a)(2)(c)(i) of the Code and will be determined by the Board on the basis of such medical evidence as the Board deems warranted under the circumstances. 

(p)    “Effective Date” means the effective date of this Plan,
which is the earlier of (i) the date that this Plan is first approved by the Company’s Stockholders, and (ii) the date this Plan is adopted by the Board. 

(q)    “Employee” means any person employed by the Company or
an Affiliate. However, service solely as a Director, or payment of a fee for such services, will not cause a Director to be considered an “Employee” for purposes of the Plan. 

(r)    “Entity” means a corporation, partnership, limited liability
company or other entity. 
 (s)    “Exchange Act Person”
means any natural person, Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act), except that “Exchange Act Person” will not include (i) the Company or any Subsidiary of the Company,
(ii) any employee benefit plan of the Company or any Subsidiary of the Company or any trustee or other fiduciary holding securities under an employee benefit plan of the Company or any Subsidiary of the Company, (iii) an underwriter
temporarily holding securities pursuant to an offering of such securities, (iv) an Entity Owned, directly or indirectly, by the Company’s Stockholders of the Company in substantially the same proportions as their Ownership of securities of
the Company; or (v) any natural person, Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act) that, as of the Effective Date, is the Owner, directly or indirectly, of securities of the Company
representing more than 50% of the combined voting power of the Company’s then outstanding securities. 

 (t)    “Exchange
Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder. 

(u)    “Fair Market Value” means, as of any date, the value of
the Shares determined reasonably and in good faith by the Board. 

(v)    “Officer” means any person designated by the Company as
an officer.  
 (w)    “Option Agreement” means a written agreement
between the Company and an Optionholder evidencing the terms and conditions of an Option grant. Each Option Agreement will be subject to the terms and conditions of the Plan. 

(x)    “Option” means an option to purchase Shares granted pursuant to the
Plan. 
 (y)    “Optionholder” means a person to whom an Option is granted
pursuant to the Plan or, if applicable, such other person who holds an outstanding Option. 

(z)    “Other Service Provider” means any provider of services
to the Company or an Affiliate other than an Employee, Director or Consultant. Other Service Providers will include, without limitation, a Shareholder who is providing services to the Company either in such Shareholder’s capacity as a
Shareholder or in some other capacity; a “director” of the Company or an Affiliate as such term may be defined in the applicable governing documents of such Entity; or a partner of an Affiliate organized as a partnership if such partner is
providing services to the Affiliate either in such partner’s capacity as a partner, or in some other capacity. 

(aa)    “Own,” “Owned,”
“Owner,” “Ownership” A person or Entity will be deemed to “Own,” to have “Owned,” to be the “Owner” of, or to have acquired “Ownership” of securities if such
person or Entity, directly or indirectly, through any contract, arrangement, understanding, relationship or otherwise, has or shares voting power, which includes the power to vote or to direct the voting, with respect to such securities. 

(bb)    “Participant” means a person to whom an Award is
granted pursuant to the Plan or, if applicable, such other person who holds an outstanding Award.  

(cc)    “Plan” means this Amended and Restated Avidity Biosciences, Inc.
2013 Equity Incentive Plan. 
 (dd)    “Rule 405” means Rule 405
promulgated under the Securities Act. 
 (ee)    “Rule 701” means Rule 701
promulgated under the Securities Act. 
 (ff)    “Securities Act” means
the Securities Act of 1933, as amended. 

 (gg)    “Share” means a
Share of Common stock of the Company, par value $0.0001. 
 (hh)    “Stockholder
Documents” means the Company’s bylaws any applicable shareholders agreement, investor rights agreement, voting agreement, drag-along agreement, right of first refusal and co-sale agreement or
similar agreement to which the Company and/or the holders of its capital securities or options may be a party that may be in effect from time to time (each, as amended or modified from
time-to-time). 

(ii)    “Subsidiary” means, with respect to the Company,
(i) any corporation of which more than 50% of the outstanding capital stock having ordinary voting power to elect a majority of the board of directors of such corporation (irrespective of whether, at the time, stock of any other class or
classes of such corporation will have or might have voting power by reason of the happening of any contingency) is at the time, directly or indirectly, Owned by the Company, and (ii) any partnership, limited liability company or other entity in
which the Company has a direct or indirect interest (whether in the form of voting or participation in profits or capital contribution) of more than 50%. 

 AVIDITY BIOSCIENCES, INC. 

OPTION GRANT NOTICE 

(AMENDED AND RESTATED 2013 EQUITY INCENTIVE PLAN)

 Avidity Biosciences, Inc. (the “Company”), pursuant to its Amended and Restated 2013 Equity Incentive Plan (the
“Plan”), hereby grants to Optionholder an option to purchase the number of Shares set forth below. This option is subject to all of the terms and conditions as set forth in this notice, in the Option Agreement, the Plan and
the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined in this notice but defined in the Plan or the Option Agreement will have the same definitions as in the Plan
or the Option Agreement. If there is any conflict between the terms in this notice and the Plan, the terms of the Plan will control. 
  

			
	Optionholder:	  	 
		
	Date of Grant:	  	 
		
	Vesting Commencement Date:	  	 
		
	Number of Shares Subject to Option:	  	 
		
	Exercise Price (Per Shares):	  	 
		
	Total Exercise Price:	  	 
		
	Expiration Date:	  	 

  

			
	Exercise Schedule:	  	☐  Same as Vesting Schedule            ☐  Early Exercise Permitted
		
	Vesting Schedule:	  	[To be specified in individual agreements] 
		
	Payment:	  	 By one or a combination of the following items (described in the Option Agreement):

 
     ☐  Cash, check, bank draft or money order
payable to the Company
     ☐  A “net exercise” arrangement (subject to the Company’s consent at the time
of exercise)

 Additional Terms/Acknowledgements: By accepting this option, Optionholder consents to receive such documents by
electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company. Optionholder acknowledges
receipt of, and understands and agrees to, this Option Grant Notice, the Option Agreement and the Plan. Optionholder acknowledges and agrees that this Option Grant Notice and the Option Agreement may not be modified, amended or revised except as
provided in a writing signed by the Optionholder and a duly authorized officer of the Company or as otherwise provided in the Plan. Optionholder further acknowledges that as of the Date of Grant, this Option Grant Notice, the Option Agreement and
the Plan set forth the entire understanding between Optionholder and the Company regarding this option award and supersede all prior oral and written agreements, promises and/or representations on that subject with the exception of (i) options
previously granted and delivered to Optionholder, and (ii) the following agreements only: the Company’s bylaws any applicable stockholders agreement, investor rights agreement, voting agreement, drag-along agreement, right of first refusal
and co-sale agreement or similar agreement to which the Company and/or the holders of its capital securities or options may be a party that may be in effect from time to time (each, as amended or modified from
time-to-time). 

									
	AVIDITY BIOSCIENCES, INC.	 		 	OPTIONHOLDER:
				
	By:	 	 	 		 	 
		 	Signature	 		 	Signature
					
	Title:	 	 	 		 	Date:	 	                    
					
	Date:	 	 	 		 		 	
	
	ATTACHMENTS: Option Agreement, 2013 Equity Incentive Plan and Notice of Exercise

 AVIDITY BIOSCIENCES, INC. 

AMENDED AND RESTATED 2013 EQUITY INCENTIVE PLAN

 OPTION AGREEMENT 

Pursuant to your Option Grant Notice (“Grant Notice”) and this Option Agreement, Avidity Biosciences, Inc. (the
“Company”) has granted you an option under its Amended and Restated 2013 Equity Incentive Plan (the “Plan”) to purchase the Shares indicated in your Grant Notice at the exercise price indicated in your
Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “Date of Grant”). If there is any conflict between the terms in this Option Agreement and the Plan, the terms of
the Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan will have the same definitions as in the Plan. This option is not intended to be an “incentive stock
option” within the meaning of Section 422 of the Code. 
 The details of your option, in addition to those set forth in the Grant
Notice and the Plan, are as follows: 
 1.    VESTING. Your option will vest as provided in
your Grant Notice. Vesting will cease upon the termination of your Continuous Service. 

2.    NUMBER OF SHARES AND EXERCISE
PRICE. The number of Shares subject to your option and your exercise price per Shares in your Grant Notice will be adjusted for Capitalization Adjustments. 

3.    EXERCISE RESTRICTION FOR
NON-EXEMPT EMPLOYEES. If you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (that is, a
“Non-Exempt Employee”), and except as otherwise provided in the Plan, you may not exercise your option until you have completed at least six months of Continuous Service measured from the Date of
Grant, even if you have already been an employee for more than six months. Consistent with the provisions of the Worker Economic Opportunity Act, you may exercise your option as to any vested portion prior to such six month anniversary in the case
of (i) your death or disability, (ii) a Company Transaction in which your option is not assumed, continued, or substituted, (iii) a Change in Control or (iv) your termination of Continuous Service on your “retirement”
(as defined in the Company’s benefit plans). 
 4.    EXERCISE PRIOR
TO VESTING (“EARLY EXERCISE”). If permitted in your Grant Notice (that is, the “Exercise Schedule” indicates “Early Exercise Permitted”) and subject to the
provisions of your option, you may elect at any time that is both (i) during the period of your Continuous Service and (ii) during the term of your option, to exercise all or part of your option, including the unvested portion of your
option; provided, however, that: 
 (a)    a partial exercise of your option will be deemed to cover first
vested Shares and then the earliest vesting installment of unvested Shares; 

 (b)    any Shares so purchased from installments that have not
vested as of the date of exercise will be subject to the purchase option in favor of the Company as described in the Company’s form of Early Exercise Shares Purchase Agreement; and 

(c)    you will enter into the Company’s form of Early Exercise Shares Purchase Agreement with a vesting
schedule that will result in the same vesting as if no early exercise had occurred. 

5.    METHOD OF PAYMENT. You must pay the full amount of the
exercise price for the Shares you wish to purchase. You may pay the exercise price in cash or by check, bank draft or money order payable to the Company or in any other manner permitted by your Grant Notice, which may include
one or more of the following: 
 (a)    By a “net exercise” arrangement pursuant to which the Company
will reduce the number of Shares issued upon exercise of your option by the largest whole number of Shares with a Fair Market Value that does not exceed the aggregate exercise price. You must pay any remaining balance of the aggregate exercise price
not satisfied by the “net exercise” in cash or other permitted form of payment. Shares will no longer be outstanding under your option and will not be exercisable thereafter if those Shares (i) are used to pay the exercise price
pursuant to the “net exercise,” (ii) are delivered to you as a result of such exercise, or (iii) are withheld to satisfy your tax withholding obligations. 

6.    WHOLE SHARES. You may exercise your option only for whole Shares. 

7.    SECURITIES LAW COMPLIANCE. In no event may you exercise
your option unless the Shares issuable upon your exercise are then registered under the Securities Act or, if not registered, the Company has determined that your exercise and the issuance of the Shares would be exempt from the registration
requirements of the Securities Act. The exercise of your option also must comply with all other applicable laws and regulations governing your option, and you may not exercise your option if the Company determines that your exercise would not
be in material compliance with such laws and regulations (including any restrictions on exercise required for compliance with Treas. Reg. 1.401(k)-1(d)(3), if applicable). 

8.    TERM. You may not exercise your option before the Date of Grant or after the expiration
of the option’s term. The term of your option expires, subject to the provisions in the Plan, upon the earliest of the following: 

(a)    immediately upon the termination of your Continuous Service for Cause; 

(b)    three months after the termination of your Continuous Service for any reason other than Cause, your
Disability or your death (except as otherwise provided in Section 8(d) below); provided, however, that if during any part of such three month period your option is not exercisable solely because of the condition set forth in the section
above relating to “Securities Law Compliance,” your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate period of three months after the termination of

 
your Continuous Service; provided further, that if (i) you are a Non-Exempt Employee, (ii) your Continuous Service terminates within six
months after the Date of Grant, and (iii) a portion of your option has vested at the time of your Continuous Service termination, your option will not expire until the earlier of (x) the later of (A) the date that is seven months
after the Date of Grant, and (B) the date that is three months after the termination of your Continuous Service, and (y) the Expiration Date; 

(c)    12 months after the termination of your Continuous Service due to your Disability (except as otherwise
provided in Section 8(d) below); 
 (d)    18 months after your death if you die either during your
Continuous Service or within three months after your Continuous Service terminates for any reason other than Cause; 

(e)    the Expiration Date indicated in your Grant Notice; or 

(f)     the day before the 10th anniversary of the Date of
Grant. 
 9.    EXERCISE. 

(a)    You may exercise the vested portion of your option (and the unvested portion of your option if your Grant
Notice so permits) during its term by (i) delivering a Notice of Exercise (in a form designated by the Company) or completing such other documents and/or procedures designated by the Company for exercise, and (ii) paying the exercise price
and any applicable withholding taxes to the Company’s Secretary, stock plan administrator or to such other person as the Company may designate, together with such additional documents as the Company may then require. 

(b)    By exercising your option you agree that, as a condition to any exercise of your option, the Company may
require you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (i) the exercise of your option, (ii) the lapse of any substantial risk of
forfeiture to which the Shares are subject at the time of exercise, or (iii) the disposition of Shares acquired upon such exercise. 

(c)    By exercising your option you agree that you will not sell, dispose of, transfer, make any short sale of,
grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any Shares or other securities of the Company held by you, for a period of 180 days following the effective date of a
registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate with FINRA Rule 2241 or any successor or similar rule or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this section will prevent the exercise of a reacquisition or repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are 

 
consistent with the foregoing or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to
your Shares until the end of such period. You also agree that any transferee of any Shares held by you will be bound by this Section 9(c). The underwriters of the Company’s securities are intended third party beneficiaries of this
Section 9(c) and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto. 

10.    TRANSFERABILITY. Except as otherwise provided in this Section 10, your option is
not transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you. 

(a)    Certain Trusts. Upon receiving written permission from the Board or its duly authorized designee, you
may transfer your option to a trust if you are considered to be the sole beneficial owner (determined under Section 671 of the Code and applicable state law) while the option is held in the trust. You and the trustee must enter into transfer
and other agreements required by the Company. 
 (b)    Domestic Relations Orders. Upon receiving written
permission from the Board or its duly authorized designee, and provided that you and the designated transferee enter into transfer and other agreements required by the Company, you may transfer your option pursuant to the terms of a domestic
relations order, official marital settlement agreement or other divorce or separation instrument that contains the information required by the Company to effectuate the transfer. You are encouraged to discuss the proposed terms of any division of
this option with the Company prior to finalizing the domestic relations order or marital settlement agreement to help ensure the required information is contained within the domestic relations order or marital settlement agreement. 

(c)    Beneficiary Designation. Upon receiving written permission from the Board or its duly authorized
designee, you may, by delivering written notice to the Company, in a form approved by the Company and any broker designated by the Company to handle option exercises, designate a third party who, on your death, will thereafter be entitled to
exercise this option and receive the Shares or other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate will be entitled to exercise this option and receive, on behalf of
your estate, the Shares or other consideration resulting from such exercise. 
 11.    RIGHT
OF FIRST REFUSAL; TRANSFER RESTRICTIONS ON SHARES. Shares that you acquire upon exercise of your option are subject to any right of first
refusal or other transfer restrictions that may be described in the Stockholder Documents in effect at such time the Company elects to exercise its right. The Company’s right of first refusal will expire on the first date upon which any
security of the Company is listed (or approved for listing) upon notice of issuance on a national securities exchange or quotation system. 

 12.    RIGHT OF
REPURCHASE. To the extent provided in the Stockholder Documents in effect at such time the Company elects to exercise its right, the Company will have the right to repurchase all or any part of the Shares you acquire pursuant to
the exercise of your option. 
 13.    OPTION NOT A
SERVICE CONTRACT. Your option is not an employment or service contract, and nothing in your option will be deemed to create in any way whatsoever any obligation on your part to continue in the employ or service of
the Company or an Affiliate, or of the Company or an Affiliate to continue your employment or service. In addition, nothing in your option will obligate the Company or an Affiliate, their respective owners, managers, directors, officers or employees
to continue any relationship that you might have as a manager, director or consultant for the Company or an Affiliate. 

14.    WITHHOLDING OBLIGATIONS. 

(a)    At the time you exercise your option, in whole or in part, and at any time thereafter as requested by the
Company, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for, any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the
Company or an Affiliate, if any, which arise in connection with the exercise of your option. 
 (b)    Upon your
request and subject to approval by the Company, in its sole discretion, and compliance with any applicable legal conditions or restrictions, the Company may withhold from fully vested Shares otherwise issuable to you upon the exercise of your option
a number of whole Shares having a Fair Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law (or such lower amount as may be necessary to avoid classification of
your option as a liability for financial accounting purposes). If the date of determination of any tax withholding obligation is deferred to a date later than the date of exercise of your option, Shares withholding pursuant to the preceding sentence
will not be permitted unless you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of Shares acquired upon such exercise with respect to which such determination is otherwise deferred, to
accelerate the determination of such tax withholding obligation to the date of exercise of your option. Notwithstanding the filing of such election, Shares will be withheld solely from fully vested Shares determined as of the date of exercise of
your option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such Shares withholding procedure will be your sole responsibility. 

(c)    You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate
are satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no obligation to issue a certificate for, or otherwise evidence the issuance to you of, such Shares or
release such Shares from any escrow provided for herein, if applicable, unless such obligations are satisfied. 

 15.    TAX
CONSEQUENCES. You hereby agree that the Company does not have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim
against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the
Code only if the exercise price per Shares specified in the Grant Notice is at least equal to the “fair market value” per Shares on the Date of Grant and there is no other impermissible deferral of compensation associated with the option.
Because the Shares are not traded on an established securities market, the Fair Market Value is determined by the Board, perhaps in consultation with an independent valuation firm retained by the Company. You acknowledge that there is no guarantee
that the Internal Revenue Service will agree with the valuation as determined by the Board, and you will not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates in the event that the Internal Revenue
Service asserts that the valuation determined by the Board is less than the “fair market value” as subsequently determined by the Internal Revenue Service. 

16.    NOTICES. Any notices provided for in your option or the Plan will be given in writing
(including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, 5 days after deposit in the United States mail, postage prepaid, addressed to you at the last address
you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to your participation in the Plan and your option by electronic means or to request your consent to participate in the Plan by electronic
means. By accepting this option, you consent to receive such documents by electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or
another third party designated by the Company. 
 17.    GOVERNING PLAN
DOCUMENT. Your option is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations, which may from
time to time be promulgated and adopted pursuant to the Plan. If there is any conflict between the provisions of your option and those of the Plan, the provisions of the Plan will control. 

 NOTICE OF EXERCISE 

 

					
	Avidity Biosciences, Inc.	 		  	
	10975 N Torrey Pines, #150	 		  	
	La Jolla, CA 92037	 		  	Date of
Exercise:                                 

 Ladies and Gentlemen: 

This constitutes notice to Avidity Biosciences, Inc. (the “Company”) under my option that I elect to purchase the
below number of Shares of the Company (the “Shares”) for the price set forth below. 
  

					
	 Option dated:
	  			
		  	  
	  
	 
		
	 Number of Shares as to which option is exercised:
	  			
		  	  
	  
	 
		
	 Shares to be issued in name of:
	  			
		  	  
	  
	 
		
	 Total exercise price:
	  	$	                     	 
		  	  
	  
	 
		
	 Cash payment delivered herewith:
	  	$	                     	 
		  	  
	  
	 

 By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the
terms of the Company’s 2013 Equity Incentive Plan, and (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option. 

I hereby make the following certifications and representations with respect to the number of Shares listed above, which are being acquired by
me for my own account upon exercise of the option as set forth above: 
 I acknowledge that the Shares have not been registered under the
Securities Act of 1933, as amended (the “Securities Act”), and are deemed to constitute “restricted securities” under Rule 701 and Rule 144 promulgated under the Securities Act. I warrant and represent to the
Company that I have no present intention of distributing or selling said Shares, except as permitted under the Securities Act and any applicable state securities laws. 

 I further acknowledge that I will not be able to resell the Shares for at least 90 days
after the Company becomes publicly traded (i.e., subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934) under Rule 701 and that more restrictive conditions apply to affiliates of the Company
under Rule 144. 
 I further acknowledge that certificates (if any) representing any of the Shares subject to the provisions of the option
will have endorsed thereon appropriate legends reflecting the foregoing limitations, as well as any legends reflecting restrictions pursuant to the Company’s Certificate of Incorporation, Bylaws and/or applicable securities laws. 

I further agree that, if required by the Company (or a representative of the underwriters) in connection with the first underwritten
registration of the offering of any securities of the Company under the Securities Act, I will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the
same economic effect as a sale, any Shares or other securities of the Company, for a period of 180 days following the effective date of a registration statement of the Company filed under the Securities Act (or such longer period as the underwriters
or the Company shall request to facilitate compliance with FINRA Rule 2241 any successor or similar rule or regulation). I further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters
that are consistent with the foregoing or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to my Shares subject to the foregoing
restrictions until the end of such period. 
  

	
	Very truly yours,

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