Document:

EX-4.3

 Exhibit 4.3 

THIS WARRANT AND THE SHARES 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 AND PURSUANT TO THE PROVISIONS OF ARTICLE 5 BELOW, MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND APPLICABLE STATE SECURITIES LAW OR,
IN THE OPINION OF LEGAL COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS EXEMPT FROM REGISTRATION. 

WARRANT TO PURCHASE STOCK 
  

			
	Company:	  	CATALYST BIOSCIENCES, INC., a Delaware corporation
	Number of Shares:	  	33,750
	Class of Stock:	  	Series A Preferred
	Warrant Price:	  	$1.00 per share
	Issue Date:	  	March 3rd, 2005
	Expiration Date:	  	The greater of (a) the date seven (7) years after an initial public offering of Borrower’s stock; or (b) the date ten (10) years from the Issue Date

 THIS WARRANT CERTIFIES THAT, for the agreed upon value of $1.00 and for other good and valuable
consideration, SILICON VALLEY BANK (“Holder”) is entitled to purchase the number of fully paid and nonassessable shares of the class of securities (the “Shares”) of the company (the “Company”) at the Warrant Price all
as set forth above and as adjusted pursuant to Article 2 of this Warrant, subject to the provisions and upon the terms and conditions set forth in this Warrant. 

ARTICLE 1.     EXERCISE. 

1.1       Method of Exercise. Holder may exercise this Warrant by delivering a duly executed
Notice of Exercise in substantially the form attached as Appendix 1 to the principal office of the Company. Unless Holder is exercising the conversion right set forth in Article 1.2, Holder shall also deliver to the Company a check, wire
transfer (to an account designated by the Company), or other form of payment acceptable to the Company for the aggregate Warrant Price for the Shares being purchased. 

1.2       Conversion Right. In lieu of exercising this Warrant as specified in Article 1.1,
Holder may from time to time convert this Warrant, in whole or in part, into a number of Shares determined by dividing (a) the aggregate fair market value of the Shares or other securities otherwise issuable upon exercise of this Warrant minus
the aggregate Warrant Price of such Shares by (b) the fair market value of one Share. The fair market value of the Shares shall be determined pursuant to Article 1.3. 

1.3       Fair Market Value. If the Company’s common stock is traded in a public market
and the Shares are common stock, the fair market value of each Share shall be the closing price of a Share reported for the business day immediately before Holder delivers its Notice of Exercise to the Company (or in the instance where the Warrant
is exercised immediately prior to the effectiveness of the Company’s initial public offering, the “price to public” per share price specified in the final prospectus relating to such offering). If the Company’s common stock is
traded in a public market and the Shares are preferred stock, the fair market value of a Share shall be the closing price of a share of the Company’s common stock reported for the business day immediately before Holder delivers its Notice of
Exercise to the Company (or, in the instance 

  
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where the Warrant is exercised immediately prior to the effectiveness of the Company’s initial public offering, the initial “price to public” per share price specified in the final
prospectus relating to such offering), in both cases, multiplied by the number of shares of the Company’s common stock into which a Share is convertible. If the Company’s common stock is not traded in a public market, the Board of
Directors of the Company shall determine fair market value in its reasonable good faith judgment. 

1.4       Delivery of Certificate and New Warrant. Promptly after Holder exercises or
converts this Warrant and, if applicable, the Company receives payment of the aggregate Warrant Price, the Company shall deliver to Holder certificates for the Shares acquired and, if this Warrant has not been fully exercised or converted and has
not expired, a new Warrant representing the Shares not so acquired. 
 1.5       Replacement
of Warrants. 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 and amount to the Company or, in the case of mutilation, or surrender and cancellation of this Warrant, the Company shall execute and deliver, in lieu of this Warrant, a new warrant of like tenor. 

1.6       Treatment of Warrant Upon Acquisition of Company. 

1.6.1     “Acquisition”. For the purpose of this Warrant, “Acquisition” means any
sale, license, or other disposition of all or substantially all of the assets of the Company, or any reorganization, consolidation, or merger of the Company where the holders of the Company’s securities before the transaction beneficially own
less than 50% of the outstanding voting securities of the surviving entity after the transaction. 

1.6.2     Treatment of Warrant at Acquisition. 

(a)       Upon the written request of the Company, Holder agrees that, in the event of an
Acquisition that is not an asset sale and in which the sole consideration is cash, either (i) Holder shall exercise its conversion or purchase right under this Warrant and such exercise will be deemed effective immediately prior to the
consummation of such Acquisition; or (ii) if Holder elects not to exercise the Warrant, this Warrant will expire upon the consummation of such Acquisition. The Company shall provide the Holder with written notice of its request relating to the
foregoing (together with such reasonable information as the Holder may request in connection with such contemplated Acquisition giving rise to such notice), which is to be delivered to Holder not less than ten (10) days prior to the closing of
the proposed Acquisition. 
 (b)       Upon the written request of the Company, Holder agrees
that, in the event of an Acquisition that is a sale of all or substantially all of the Company’s assets (and only its assets) to a third party that is not an Affiliate (as defined below) of the Company (a “Third Party Asset Sale”),
either (i) Holder shall exercise its conversion or purchase right under this Warrant and such exercise will be deemed effective immediately prior to the consummation of such Acquisition; or (ii) if Holder elects not to exercise the
Warrant, this Warrant will continue until the Expiration Date if the Company continues as a going concern following the closing of any such Third Party Asset Sale. The Company shall provide the Holder with written notice of its request relating to
the foregoing (together with such reasonable information as the Holder may request in connection with such contemplated Acquisition giving rise to such notice), which is to be delivered to Holder not less than ten (10) days prior to the closing
of the proposed Acquisition. 
 (c)       Upon the closing of any Acquisition other than those
particularly described in subsections (a)and (b) above, the successor entity shall assume the obligations of this Warrant, and this Warrant shall be exercisable for the same securities, cash, and property as would be payable for the Shares
issuable upon exercise of the unexercised portion of this Warrant as if such Shares were outstanding on the record date for the Acquisition and subsequent closing. The Warrant Price and/or number of Shares shall be adjusted accordingly. 

  
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 (d)       Notwithstanding the foregoing provisions of
this Section 1.6.2., in the event that the acquiror in an Acquisition does not agree to assume this Warrant at and as of the closing thereof, this Warrant, to the extent not exercised or converted on or prior to such closing, shall terminate
and be of no further force or effect as of immediately following such closing if all of the following conditions are met: (i) the acquiror is subject to the reporting requirements of Section 13 or Section 15(d) of the Securities
Exchange Act of 1934, as amended, (ii) the class of stock or other security of the acquiror that would be received by Holder in connection with such Acquisition were Holder to exercise or convert this Warrant on or prior to the closing thereof
is listed for trading on a national securities exchange or approved for quotation on an automated inter-dealer quotation system, (iii) the value (determined as of the closing of such Acquisition in accordance with the definitive agreements
therefor) of the acquiror stock and/or other securities that would be received by Holder in respect of each Share were Holder to exercise or convert this Warrant on or prior to the closing of such Acquisition is equal to or greater than three
(3) times the then-effective Warrant Price, and (iv) Holder would be able to publicly resell all of the acquiror stock and/or other securities that would be received by Holder in such Acquisition were Holder to exercise or convert this
Warrant on or prior to the closing of such Acquisition during the three (3) month period immediately following the closing thereof pursuant to an effective registration statement under the covering such acquiror stock and/or other securities or
pursuant to the provisions of Rule 144 under the Act. 
 (e)       As used herein
“Affiliate” shall mean any person or entity that owns or controls directly or indirectly twenty-five percent (25%) or more of the stock of Company, any person or entity that controls or is controlled by or is under common control with
such persons or entities, and each of such person’s or entity’s officers, directors, or partners, as applicable. 
 ARTICLE
2     ADJUSTMENTS TO THE SHARES. 
 2.1      Stock
Dividends, Splits, Etc. If the Company declares or pays a dividend on the Shares payable in common stock, or other securities, then upon exercise of this Warrant, for each Share acquired, Holder shall receive, without cost to Holder, the total
number and kind of securities to which Holder would have been entitled had Holder owned the Shares of record as of the date the dividend occurred. If the Company subdivides the Shares by reclassification or otherwise into a greater number of shares
or takes any other action which increase the amount of stock into which the Shares are convertible, the number of shares purchasable hereunder shall be proportionately increased and the Warrant Price shall be proportionately decreased. If the
outstanding shares are combined or consolidated, by reclassification or otherwise, into a lesser number of shares, the Warrant Price shall be proportionately increased and the number of Shares shall be proportionately decreased. 

2.2      Reclassification, Exchange, Combinations or Substitution. Upon any
reclassification, exchange, substitution, or other event that results in a change of the number and/or class of the securities issuable upon exercise or conversion of this Warrant, Holder shall be entitled to receive, upon exercise or conversion of
this Warrant, the number and kind of securities and property that Holder would have received for the Shares if this Warrant had been exercised immediately before such reclassification, exchange, substitution, or other event. Such an event shall
include any automatic conversion of the outstanding or issuable securities of the Company of the same class or series as the Shares to common stock pursuant to the terms of the Company’s Articles or Certificate (as applicable) of Incorporation.
The Company or its successor shall promptly issue to Holder an amendment to this Warrant setting forth the number and kind of such new securities or other property issuable upon exercise or conversion of this Warrant as a result of such
reclassification, exchange, substitution or other event that results in a change of the number and/or class of securities issuable upon exercise or conversion of this 

  
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Warrant. The amendment to this Warrant shall provide for adjustments which shall be as nearly equivalent as may be practicable to the adjustments provided for in this Article 2 including, without
limitation, adjustments to the Warrant Price and to the number of securities or property issuable upon exercise of the new Warrant. The provisions of this Article 2.2 shall similarly apply to successive reclassifications, exchanges, substitutions,
or other events. 
 2.3      Adjustments for Diluting Issuances. The Warrant Price and the
number of Shares issuable upon exercise of this Warrant or, if the Shares are Preferred Stock, the number of shares of common stock issuable upon conversion of the Shares, shall be subject to adjustment, from time to time in the manner set forth in
the Company’s Articles or Certificate of Incorporation as if the Shares were issued and outstanding on and as of the date of any such required adjustment. The provisions set forth for the Shares in the Company’s Articles or Certificate (as
applicable) of Incorporation relating to the above in effect as of the Issue Date 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 Shares in the same manner as such amendment, modification or waiver affects the rights associated with all other shares of the same series and class as the Shares granted to the Holder; provided, that, notwithstanding the foregoing, the prior
written consent of the Holder shall not be required if the rights associated with the Shares are affected in a different manner due to the number of shares held by the holders thereof or due to any action taken or not taken by the holders thereof.

 2.4      No Impairment. The Company may take any corporate action (including an
amendment of its Articles or Certificate (as applicable) of Incorporation or a reorganization, transfer of assets, consolidation, merger, dissolution, issue or sale of securities or any other voluntary action) so long as (a) the Company
receives any necessary stockholder and Board of Director approvals required pursuant to the Company’s Articles or Certificate (as applicable) of Incorporation and the Delaware General Corporate Law; and (b) any such amendment to its
Articles or Certificate (as applicable) of Incorporation or any such reorganization, transfer of assets, consolidation, merger, dissolution, issue or sale of securities or any other voluntary action does not avoid or seek to avoid the observance or
performance of any of the terms to be observed or performed under this Warrant by the Company. The Company shall at all times in good faith assist in carrying out of all the provisions of this Article 2 and in taking all such action as may be
necessary or appropriate to protect Holders rights under this Article against impairment. 

2.5      Fractional Shares. No fractional Shares shall be issuable upon exercise or
conversion of the Warrant and the number of Shares to be issued shall be rounded down to the nearest whole Share. If a fractional share interest arises upon any exercise or conversion of the Warrant, the Company shall eliminate such fractional share
interest by paying Holder the amount computed by multiplying the fractional interest by the fair market value of a full Share. 

2.6      Certificate as to Adjustments. Upon each adjustment of the Warrant Price, the
Company shall promptly notify Holder in writing, and, at the Company’s expense, promptly compute such adjustment, and furnish Holder with a certificate of its Chief Financial Officer setting forth such adjustment and the facts upon which such
adjustment is based. The Company shall, upon written request, furnish Holder a certificate setting forth the Warrant Price in effect upon the date thereof and the series of adjustments leading to such Warrant Price. 

ARTICLE 3     REPRESENTATIONS AND COVENANTS OF THE COMPANY. 

3.1       Representations and Warranties. The Company represents and warrants to the
Holder as follows: 
 3.1.1      The initial Warrant Price referenced on the first page of this
Warrant is not greater than the price per share at which the Shares were last issued in an arms-length transaction in which at least $500,000 of the Shares were sold. 

  
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 3.1.2      All Shares which may be issued upon the
exercise of the purchase right represented by this Warrant, and all securities, if any, issuable upon conversion of the Shares, shall, upon issuance, be duly authorized, validly issued, fully paid and nonassessable, and free of any liens and
encumbrances except for restrictions on transfer provided for herein or under applicable federal and state securities laws. 

3.1.3      The Capitalization Table dated 19 Feb ‘05 remains true and complete as of the Issue
Date. 
 3.2      Notice of Certain Events. If the Company proposes at any time (a) to
declare any dividend or distribution upon any of its stock, whether in cash, property, stock, or other securities and whether or not a regular cash dividend; (b) ) to offer for sale any shares of the Company’s capital stock (or other
securities convertible into such capital stock), other than (i) pursuant to the Company’s stock option or other compensatory plans; (ii) in connection with commercial credit arrangements or equipment financings; or (iii) in
connection with strategic transactions for purposes other than capital raising; or series of the Company’s stock; (c) to effect any reclassification or recapitalization of any of its stock; (d) to merge or consolidate with or into any
other corporation, or sell, lease, license, or convey all or substantially all of its assets, or to liquidate, dissolve or wind up; or (e) offer holders of registration rights the opportunity to participate in an underwritten public offering of
the company’s securities for cash, then, in connection with each such event, the Company shall give Holder: (1) at least ten (10) days prior written notice of the date on which a record will be taken for such dividend, distribution,
or subscription rights (and specifying the date on which the holders of common stock will be entitled thereto) or for determining rights to vote, if any, in respect of the matters referred to in (c) and (d) above; (2) in the case of
the matters referred to in (c) and (d) above at least ten (10) days prior written notice of the date when the same will take place (and specifying the date on which the holders of common stock will be entitled to exchange their common
stock for securities or other property deliverable upon the occurrence of such event); and (3) in the case of the matter referred to in (e) above, the same notice as is given to the holders of such registration rights. 

3.3      Registration Under Securities Act of 1933, as amended. The Company agrees that the
Shares, or if the Shares are convertible into common stock of the Company, such common stock, shall have certain incidental, or “Piggyback,” registration rights pursuant to and as set forth in the Company’s Investor Rights Agreement
dated October 31, 2003, among the Company and the other parties named therein (as the same may be amended from time to time, the “Investor Rights Agreement”). The provisions set forth in the Company’s Investor Rights Agreement in
effect as of the Issue Date may not be amended, modified or waived without the prior written consent of Holder unless such amendment, modification, or waiver affects the incidental, or “Piggyback,” rights associated with the Shares in the
same manner as such amendment, modification or waiver affects such rights associated with all other shares of the same series and class as the Shares granted to the Holder; provided, that, notwithstanding the foregoing, the prior written consent of
the Holder shall not be required if such rights associated with the Shares are affected in a different manner due to the number of shares held by the holders thereof or due to any action taken or not taken by the holders thereof. 

3.4      No Shareholder Rights. Except as provided in this Warrant, the Holder will not have
any rights as a shareholder of the Company until the exercise of this Warrant. 
 ARTICLE 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 the Holder will be acquired for investment for the 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 the
Holder has not been formed for the specific purpose of acquiring this Warrant or the Shares. 

  
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 4.2      Disclosure of Information. The Holder
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. The 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 the Holder or to which the Holder has access. 

4.3      Investment Experience. The Holder understands that the purchase of this Warrant and
its underlying securities involves substantial risk. The Holder has experience as an investor in securities of companies in the development stage and acknowledges that the 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 the 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 the Holder to be aware of the character, business acumen and financial circumstances
of such persons. 
 4.4      Accredited Investor Status. The Holder is an “accredited
investor” within the meaning of Regulation D promulgated under the Act. 
 4.5      The
Act. The Holder understands that this Warrant and the Shares issuable upon exercise or conversion hereof have not been registered un 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. The Holder understands that this Warrant and the Shares issued upon any exercise or conversion hereof must be held indefinitely unless subsequently registered under the
1933 Act and qualified under applicable state securities laws, or unless exemption from such registration and qualification are otherwise available. 

ARTICLE 5     MISCELLANEOUS. 

5.1      Term. This Warrant is exercisable in whole or in part at any time and from time to
time on or before the Expiration Date. 
 5.2      Market Stand-Off Agreement. Holder
hereby agrees that Holder shall not sell or otherwise 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, of any common stock (or other
securities) of the Company during the one hundred eighty (180) day period following the effective date of the Company’s initial public offering. The obligations described in this Section 5.2 shall not apply to a registration relating
solely to employee benefit plans on Form S-1 or Form S-8 or similar forms that may be promulgated in the future, or a registration relating solely to a transaction on Form S-4 or similar forms that may be promulgated in the future. The Company may
impose stop-transfer instructions and may stamp the certificates representing the Shares (and the securities issuable, directly or indirectly, upon conversion of the Shares, if any) with a legend describing the foregoing restriction until the end of
such one hundred eighty (180) day period. Holder agrees to execute a market standoff agreement with said underwriters in customary form consistent with the provisions of this Section 5.2. The obligations under this Section 5.2 shall
apply only if all officers, directors and one-percent security holders of the Company are bound by similar agreements. 

  
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 5.3      Legends. This Warrant and the Shares
(and the securities issuable, directly or indirectly, upon conversion of the Shares, if any) shall be imprinted with a legend in substantially the following form: 

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE ACT, OR THE SECURITIES LAWS OF ANY
STATE AND, EXCEPT AND PURSUANT TO THE PROVISIONS OF ARTICLE 5 BELOW, MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND APPLICABLE STATE SECURITIES LAW OR, IN THE OPINION OF
LEGAL COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS EXEMPT FROM REGISTRATION. 

5.4      Compliance with Securities Laws on Transfer. This Warrant and the Shares issuable
upon exercise of this Warrant (and the securities issuable, directly or indirectly, upon conversion of the Shares, if any) may not be transferred or assigned in whole or in part without 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 Silicon Valley Bancshares (Holder’s parent company) or any other affiliate of Holder. Additionally, the Company shall also not require an opinion of counsel if there is no material
question as to the availability of current information as referenced in Rule 144(c), Holder represents that it has complied with Rule 144(d) and (e) in reasonable detail, the selling broker represents that it has complied with Rule 144(f), and
the Company is provided with a copy of Holder’s notice of proposed sale. 

5.5      Transfer Procedure. Upon receipt by Holder of the executed Warrant, Holder will
transfer all of this Warrant to Silicon Valley Bancshares, Holder’s parent company, by execution of an Assignment substantially in the form of Appendix 2. Subject to the provisions of Article 5.4 and upon providing Company with written
notice, Silicon Valley Bancshares and any subsequent Holder may transfer all or part of this Warrant or the Shares issuable upon exercise of this Warrant (or the Shares issuable directly or indirectly, upon conversion of the Shares, if any) to any
transferee, provided, however, in connection with any such transfer, (i) Silicon Valley Bancshares or any subsequent Holder will give the Company notice of the portion of the Warrant being transferred with the name, address and taxpayer
identification number of the transferee, (ii) Holder will surrender this Warrant to the Company for reissuance to the transferee(s) (and Holder if applicable), and (iii) the transferee(s) shall agree to be bound by the terms and conditions
of this Warrant, including without limitation the market standoff agreement set forth in Section 5.2 above. The Company may refuse to transfer this Warrant or the Shares to any person who directly competes with the Company, unless, in either
case, the stock of the Company is publicly traded. 
 5.6      Notices. All notices and
other communications from the Company to the Holder, or vice versa, shall be deemed delivered and effective when given personally or mailed by first-class registered or certified mail, postage prepaid, at such address as may have been furnished to
the Company or the Holder, as the case may (or on the first business day after transmission by facsimile) be, in writing by the Company or such holder from time to time. Effective upon receipt of the fully executed Warrant and the initial transfer
described in Article 5.5 above, all notices to the Holder shall be addressed as follows until the Company receives notice of a change of address in connection with a transfer or otherwise: 

  
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 Silicon Valley Bancshares 

Attn: Treasury Department 
 3003 Tasman Drive, HA
200 
 Santa Clara, CA 95054 
 Telephone:
408-654-7400 
 Facsimile: 408-496-2405 
 Notice to the Company
shall be addressed as follows until the Holder receives notice of a change in address: 
 Catalyst Biosciences, Inc. 

Attn: David O’Reilly 
 290 Utah Avenue 

South San Francisco CA, 94080 
 Telephone:
(415) 476-8146. 
 Facsimile: (415) 871-2475 

5.7      Waiver. This Warrant and any term hereof may be changed, waived, discharged or
terminated only by an instrument in writing signed by the party against which enforcement of such change, waiver, discharge or termination is sought. 

5.8      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 attorney’s fees. 

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

5.10      Counterparts. This Warrant may be executed in counterparts, all of which together
shall constitute one and the same agreement. 

  
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 5.11      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. 
 “COMPANY” 

 

			
	CATALYST BIOSCIENCES, INC.
		
	By:	 	 /s/ David O’Reilly

			
	Title:	 	 President

			
		
	“HOLDER”	 	
	
	SILICON VALLEY BANK

			
		
	By:	 	 

  

			
	Title:	 	 Vice President

			
	Warrant Effective Date: March 3, 2005

  
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 APPENDIX 1 

NOTICE OF EXERCISE 

1.       Holder elects to
purchase                      shares of the
Common/Series              Preferred [strike one] Stock of OUR GREATEST CUSTOMER, INC. pursuant to the terms of the attached Warrant, and tenders payment of the purchase price
of the shares in full. 
 [or] 

1.       Holder elects to convert the attached Warrant into Shares/cash [strike one] in the manner
specified in the Warrant. This conversion is exercised
for                                  of the Shares covered by the Warrant.

 [Strike paragraph that does not apply.] 
 2.
Please issue a certificate or certificates representing the shares in the name specified below: 
  

 
 Holders Name 

 
  

 
  

(Address) 
 3.     By its
execution below and for the benefit of the Company, Holder hereby restates each of the representations and warranties in Article 4 of the Warrant as the date hereof. 

 

			
	HOLDER:
	
	  

		
	By:	 	  

 
			
		
	Name:	 	  

 
			
		
	Title:	 	  

 
			
		
	(Date):	 	  

  
 10 

 ASSIGNMENT 

For value received, Silicon Valley Bank hereby sells, assigns and transfers unto: 

Name: Silicon Valley Bancshares 
 Address:
3003 Tasman Drive (HA-200) 
 Santa Clara, CA 95054 

TaxID: 91-1962278 
 that certain Warrant to Purchase
Stock issued by Catalyst Biosciences, Inc. (the “Company”), on March 3, 2005 (the
“Warrant”) together with all rights, title and interest therein. 
  

			
	SILICON VALLEY BANK
		
	By:	 	 /s/ Peter Scott

		
	Name:	 	 Peter Scott

		
	Title:	 	 SRM

 Date: 2/22/05 
 By its execution
below, and for the benefit of the Company, Silicon Valley Bancshares makes each of the representations and warranties set forth in Article 4 of the Warrant as of the date hereof. 

 

			
	SILICON VALLEY BANCSHARES
		
	By:	 	 /s/ Paulette Mehas

	Name:	 	 Paulette Mehas

	Title:	 	 TreasurerEX-4.4

 Exhibit 4.4 

THIS WARRANT AND THE SHARES PURCHASABLE HEREUNDER HAVE BEEN ACQUIRED FOR INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, OR QUALIFIED UNDER ANY STATE SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR QUALIFICATION OR AN EXEMPTION THEREFROM UNDER SAID ACT AND ANY APPLICABLE STATE SECURITIES
LAWS. 
 THIS WARRANT AND THE SHARES PURCHASABLE HEREUNDER ARE SUBJECT TO RESTRICTIONS ON TRANSFER CONTAINED IN THAT CERTAIN
SERIES E PREFERRED STOCK PURCHASE AGREEMENT, DATED APRIL __, 2014, WHICH RESTRICTIONS ON TRANSFER ARE INCORPORATED HEREIN BY REFERENCE. 

PWE-___ 
 Dated: April __, 2014

 WARRANT TO PURCHASE STOCK OF 

CATALYST BIOSCIENCES, INC. 

This certifies that ________________, or its assigns (the “Holder”), for value received, is entitled to purchase,
from Catalyst Biosciences, Inc., a Delaware corporation (the “Company”), up to that number of fully paid and nonassessable shares of the Company’s Series E Preferred Stock, equal to the quotient obtained in accordance with the
following calculation: 
  

					
	 Warrant Shares
  

(as defined below) issuable

upon exercise of this Warrant
  
	  	  
  

=    
	  	  
 The number of shares of Series E Preferred Stock issued
by the Company to Holder on the date hereof) x 0.25

 This Warrant is issued pursuant to the terms of that certain Series E Preferred Stock Purchase Agreement,
dated April __, 2014, by and among the Company and the investors set forth in the Schedule of Investors attached thereto as Exhibit A (the “Agreement”). This Warrant is one of a series of warrants (the “Warrants”) having
like tenor and effect (except for variations necessary to express the name of the holder and the date on which each Warrant is issued) issued or to be issued by the Company in accordance with the terms of the Agreement. Capitalized terms not
otherwise defined herein shall have the meanings set forth in the Agreement. 
 This Warrant shall be exercisable at any time from time to
time from and after the date hereof (such date being referred to herein as the “Initial Exercise Date”) up to and including 5:00 p.m. (Pacific Time) until the first to occur of (i) immediately prior to the closing of any Liquidation
Transaction (as defined in the Company’s Amended and Restated Certificate of Incorporation, as amended from time to time), or (ii) the 5th anniversary of the date hereof (such earlier date being referred to herein as the “Expiration
Date”), upon surrender to the Company at its principal office (or at such other location as the Company may advise the Holder in writing) of this Warrant properly endorsed with (i) the Form of Subscription attached hereto duly completed
and executed, (ii) payment pursuant to Section 2 of the aggregate Exercise Price for the number of 

 
Warrant Shares for which this Warrant is being exercised determined in accordance with the provisions hereof. Notwithstanding the foregoing, if Holder has not exercised this Warrant by the
Expiration Date, then the exercise of this Warrant shall be deemed to have been automatically effected prior to the close of business on the Expiration Date pursuant to the Net Issuance provisions in Section 2 of this Warrant. The Exercise
Price and the number of Warrant Shares purchasable hereunder are subject to adjustment as provided in Section 4 of this Warrant. 
 The
term “Warrant Shares” shall shares of the Company’s Series E Preferred Stock. 
 The term “Exercise Price” shall
mean $1.2706 per share (as adjusted for stock splits, stock dividends, reclassification and the like). 
 The term “IPO” shall
mean a Qualified IPO as defined in the Company’s Amended and Restated Certificate of Incorporation. 

1.     Exercise; Issuance of Certificates; Acknowledgement. This Warrant is exercisable at the
option of the holder of record hereof, at any time or from time to time from or after the Initial Exercise Date up to the Expiration Date for all or any part of the Warrant Shares (but not for a fraction of a share) which may be purchased hereunder.
The Company agrees that the Warrant Shares purchased hereunder shall be and are deemed to be issued to the Holder hereof as the record owner of such shares as of the close of business on the date on which this Warrant shall have been surrendered,
properly endorsed, the completed, executed Form of Subscription delivered and payment made for such shares. Certificates for the Warrant Shares so purchased, together with any other securities or property to which the Holder hereof is entitled upon
such exercise, shall be delivered to the Holder hereof by the Company at the Company’s expense within a reasonable time after the rights represented by this Warrant have been so exercised. Each certificate so delivered shall be in such
denominations of the Warrant Shares as may be requested by the Holder hereof and shall be registered in the name of such Holder. In case of a purchase of less than all the Warrant Shares, the Company shall execute and deliver to Holder within a
reasonable time an Acknowledgement in the form attached hereto indicating the number of Warrant Shares which remain subject to this Warrant, if any. 

2.     Payment for Shares. The aggregate purchase price for Warrant Shares being purchased
hereunder may be paid either (i) by cash or wire transfer of immediately available funds, (ii) by surrender of a number of Warrant Shares which have a fair market value equal to the aggregate purchase price of the Warrant Shares being
purchased (“Net Issuance”) as determined herein, or (iii) any combination of the foregoing. If the Holder elects the Net Issuance method of payment, the Company shall issue to Holder upon exercise a number of shares of Warrant Shares
determined in accordance with the following formula: 
  

					
		  	  
 Y(A-B)
	  	
	X=	  	  
	  	
		  	 A
	  	

 where: X =     the number of Warrant Shares to be issued to the Holder;

 Y =     the number of Warrant Shares with respect to which the Holder is 

  
 2 

			
		  	 exercising its purchase rights under this Warrant;
  

	A =	  	 the fair market value of one (1) share of the Warrant Shares on the

 

		  	 date of exercise; and
  

	 B =
	  	the Exercise Price.

 No fractional shares arising out of the above formula for determining the number of shares to
be issued to the Holder shall be issued, and the Company shall in lieu thereof make payment to the Holder of cash in the amount of such fraction multiplied by the fair market value of one (1) share of the Warrant Shares on the date of exercise.
For purposes of the above calculation, the fair market value of one (1) share of the Warrant Shares shall mean (a) if the date of exercise is after the commencement of trading of the Common Stock on a securities exchange or
over-the-counter but prior to the closing of the IPO, the price per share to the public set forth on the final prospectus relating to the IPO, multiplied by the number of shares of Common Stock into which each share of the Warrant Shares is then
convertible, (b) if the Common Stock is then traded on a securities exchange, the average of the closing prices of such Common Stock on such exchange over the thirty (30) calendar day period (or portion thereof) ending three (3) days
prior to the date of exercise, multiplied by the number of shares of Common Stock into which each share of the Warrant Shares is then convertible, (c) if the Common Stock is then regularly traded over-the-counter, the average of the closing
sale prices or secondarily the closing bid of such Common Stock over the thirty (30) calendar day period (or portion thereof) ending three (3) days prior to the date of exercise, multiplied by the number of shares of Common Stock into
which each share of the Warrant Shares is then convertible, or (d) if there is no active public market for the Common Stock, the fair market value of one share of the Warrant Shares as determined in good faith by the Board of Directors of the
Company . 
 3.       Shares to be Fully Paid. The Company covenants and agrees that
all Warrant Shares which may be issued upon the exercise of the rights represented by this Warrant will, upon issuance, be duly authorized, validly issued, fully paid and nonassessable and free from all preemptive rights of any stockholder and free
of all taxes, liens and charges with respect to the issue thereof. 
 4.       Adjustment
of Exercise Price and Number of Shares. The Exercise Price and the number of shares purchasable upon the exercise of this Warrant shall be subject to adjustment from time to time upon the occurrence of certain events described in this
Section 4. Upon each adjustment of the Exercise Price, the Holder of this Warrant shall thereafter be entitled to purchase, at the Exercise Price resulting from such adjustment, the number of shares obtained by multiplying the Exercise Price in
effect immediately prior to such adjustment by the number of shares purchasable pursuant hereto immediately prior to such adjustment, and dividing the product thereof by the Exercise Price resulting from such adjustment. 

4.1     Subdivisions, Combinations and Dividends. In case the Company shall at any time subdivide
its outstanding shares of capital stock into a greater number of shares or pay a dividend in capital stock in respect of outstanding shares of capital stock, the Exercise Price in effect immediately prior to such subdivision or at the record date of
such dividend shall be 

  
 3 

 
proportionately reduced, and conversely, in case the outstanding shares of the capital stock of the Company shall be combined into a smaller number of shares, the Exercise Price in effect
immediately prior to such combination shall be proportionately increased. 
 4.2    
Reclassification. If any reclassification of the capital stock of the Company shall be effected in such a way that holders thereof shall be entitled to receive stock, securities, or other assets or property, then, as a condition of such
reclassification, lawful and adequate provisions shall be made whereby the Holder hereof shall thereafter have the right to purchase and receive (in lieu of the shares of the capital stock immediately theretofore purchasable and receivable upon the
exercise of the rights represented hereby) such shares of stock, securities or other assets or property as may be issued or payable with respect to or in exchange for a number of outstanding shares of such capital stock equal to the number of shares
of such capital stock immediately theretofore purchasable and receivable upon the exercise of the rights represented hereby. In any reclassification described above, appropriate provision shall be made with respect to the rights and interests of the
Holder of this Warrant to the end that the provisions hereof (including, without limitation, provisions for adjustments of the Exercise Price and of the number of shares purchasable and receivable upon the exercise of this Warrant) shall thereafter
be applicable, as nearly as may be, in relation to any shares of stock, securities or assets thereafter deliverable upon the exercise hereof. 

4.3     Notice of Adjustment. Upon any adjustment of the Exercise Price or any increase or decrease
in the number of shares purchasable upon the exercise of this Warrant, the Company shall give written notice thereof, by first class mail postage prepaid, addressed to the registered Holder of this Warrant at the address of such Holder as shown on
the books of the Company. The notice shall be signed by the Company’s Chief Financial Officer and shall state the Exercise Price resulting from such adjustment and the increase or decrease, if any, in the number of shares purchasable at such
price upon the exercise of this Warrant, setting forth in reasonable detail the method of calculation and the facts upon which such calculation is based. 

4.4     Other Notices. If at any time: 

 (1) the Company shall declare any cash dividend upon its capital stock; or 

 (2) there shall be any Liquidation Transaction. 

then, in any one or more of said cases, the Company shall give, by first class mail, postage prepaid, addressed to the Holder of this Warrant
at the address of such Holder as shown on the books of the Company, (a) at least ten (10) days prior written notice of the date on which the books of the Company shall close or a record shall be taken for such dividend or for determining
rights to vote in respect of any such reorganization, reclassification, consolidation, merger, sale, dissolution, liquidation or winding-up, and (b) in the case of any such reorganization, reclassification, consolidation, merger, sale,
dissolution, liquidation, winding-up or public offering, at least ten (10) days prior written notice of the date when the same shall take place; provided, however, that the Holder shall make a best efforts attempt to respond to such notice as
early as possible after the receipt thereof. Any notice given in accordance with the foregoing clause (a) shall also specify, in the case of any such dividend, the date on which the holders of 

  
 4 

 
capital stock shall be entitled thereto. Any notice given in accordance with the foregoing clause (b) shall also specify the date on which the holders of capital stock shall be entitled to
exchange their capital stock for securities or other property deliverable upon such reorganization, reclassification, consolidation, merger, sale, dissolution, liquidation, winding-up, conversion or public offering, as the case may be. 

5.     No Voting or Dividend Rights. Nothing contained in this Warrant shall be construed as
conferring upon the Holder hereof the right to vote or to consent to receive notice as a stockholder of the Company or any other matters or any rights whatsoever as a stockholder of the Company. No dividends or interest shall be payable or accrued
in respect of this Warrant or the interest represented hereby or the shares purchasable hereunder until, and only to the extent that, this Warrant shall have been exercised. 

6.     Warrants Non-Transferable. Neither this Warrant nor any of the rights hereunder may be
transferred, in whole or in part, without the prior written consent of the Company. 
 7.     Lost
Warrants. Upon receipt of evidence reasonably satisfactory to the Company of the loss, theft, destruction, or mutilation of this Warrant and, in the case of any such loss, theft or destruction, upon receipt of an indemnity reasonably
satisfactory to the Company, or in the case of any such mutilation upon surrender and cancellation of such Warrant, the Company, at its expense, will make and deliver a new Warrant, of like tenor, in lieu of the lost, stolen, destroyed or mutilated
Warrant. 
 8.     Amendment. Any term of this Warrant and all Warrants issued pursuant to the
Agreement may be amended and the observance of any term of this Warrant and all Warrants issued pursuant to the Agreement may be waived (either generally or in a particular instance and either retroactively or prospectively), only with the written
consent of the Company and the holders of Warrants representing 66 2/3% of the Warrant Shares issued pursuant to the Agreement; provided any such amendment or waiver that affects by its terms any holder(s) in a manner that is different in any
material respect from all holders shall require the approval of the Company, such holder(s) and the holders of 66 2/3% of the Warrant Shares issued pursuant to the Agreement. Any amendment or waiver effected in accordance with this paragraph shall
be binding upon the Company, the Holder and the holders of all Warrants issued pursuant to the Agreement. 

9.     Notices. Except as may be otherwise provided herein, all notices, requests, waivers and
other communications made pursuant to this Warrant shall be made in accordance with Section 7.2 of the Agreement. 

10.     Governing Law; Venue. This Warrant is to be construed in accordance with and governed by
the internal laws of the State of California without giving effect to any choice of law rule that would cause the application of the laws of any jurisdiction other than the internal laws of the State of California to the rights and duties of the
parties. All disputes and controversies arising out of or in connection with this Warrant shall be resolved exclusively by the state and federal courts located in Santa Clara County in the State of California, and each party hereto agrees to submit
to the jurisdiction of said courts and agrees that venue shall lie exclusively with such courts. 

  
 5 

*        *        * 

  
 6 

 IN WITNESS WHEREOF, the Company has caused this Warrant to be duly executed by
its officers, thereunto duly authorized as of the date first above written. 
  

			
	 CATALYST BIOSCIENCES, INC.
  

	By:                                   
                              
	  
 Name: Nassim
Usman                                   

 

	Title: Chief Executive Officer                       

 FORM OF SUBSCRIPTION 

(To be signed only upon exercise of Warrant) 

To: Catalyst Biosciences, Inc. 

The undersigned, the holder of a right to purchase shares of Catalyst Biosciences, Inc., a Delaware corporation (the
“Company”), pursuant to that certain Warrant to Purchase Stock of the Company (the “Warrant”), dated as of April __, 2014, hereby irrevocably elects to exercise the purchase right represented by such Warrant for, and to purchase
thereunder, __________________________ (            ) shares of ____________ Stock of the Company and herewith makes payment of ________________________ Dollars ($__________)
therefor by the following method: 
  

			
	 (Check one of the following):

 
	  	
	 _______ (check if applicable)
	  	 The undersigned hereby elects to make payment of

		  	 ______________ Dollars ($___________) therefor in cash.

 

	 _______ (check if applicable)
	  	 The undersigned hereby elects to make payment for the aggregate exercise price of this exercise using the Net Issuance method pursuant to Section 2 of the
Warrant.

 The undersigned represents that it is acquiring such securities for its own account for
investment and not with a view to or for sale in connection with any distribution thereof and in order to induce the issuance of such securities makes to the Company, as of the date hereof, the representations and warranties set forth in
Section 4 of the Series E Preferred Stock Purchase Agreement, dated as of April __, 2014, by and among the Company and the investors listed on Exhibit A thereto. 

DATED: ________________ 
  

			
	 [HOLDER NAME]
  

	By:                                   
                               
	
	  

Name:                         
                                    

	
	  

Its:                         
                                         
  

 ACKNOWLEDGMENT 

To: ______________________ 
 The
undersigned hereby acknowledges that as of the date hereof, __________________ (            ) shares remain subject to the right of purchase in favor of ________________ pursuant to
that certain Warrant to Purchase Stock of Catalyst Biosciences, Inc., dated as of April __, 2014. 
 DATED: ________________ 

 

			
	CATALYST BIOSCIENCES, INC.
	
	  

By:                         
                                         

	
	  

Name:                         
                                    

	
	  

Title:

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