Amendment No.1 to Rights Agreement



 Exhibit 4.1 

AMENDMENT NO. 1 TO RIGHTS AGREEMENT 

This AMENDMENT NO. 1 TO RIGHTS AGREEMENT, dated as of September 19, 2016 (the “Amendment”), amends that certain Rights
Agreement, dated as of September 20, 2011 (the “Rights Agreement”), between Catalyst Pharmaceuticals, Inc. (f/k/a Catalyst Pharmaceutical Partners, Inc., a Delaware corporation (the “Company”) and Continental Stock
Transfer and Trust Company (the “Rights Agent”). Capitalized terms used, but not otherwise defined, herein shall have the respective meanings ascribed to such terms in the Rights Agreement. 

WHEREAS, pursuant to Section 27 of the Rights Agreement, for so long as the Rights remain redeemable, the Company may, in its sole and
absolute discretion, and the Rights Agent shall if the Company so directs, supplement or amend any provisions of the Rights Agreement in any respect; and 

WHEREAS, the Rights remain redeemable and the Company wishes to amend certain provisions of the Rights Agreement, as more particularly
set forth in this Amendment. 
 NOW, THEREFORE, the Rights Agreement is hereby amended as follows: 

 

	1.	Amendments to Rights Agreement. The Rights Agreement is hereby amended as follows: 

  

	 	A.	Section 7(a) of the Rights Agreement is hereby amended in its entirety and restated to read as follows: 


(a) Subject to Section 7(e) hereof, at any time after the Distribution Date the registered holder of any Rights
Certificate may exercise the Rights evidenced thereby (except as otherwise provided herein including, without limitation, the restrictions on exercisability set forth in Section 9(c), Section 11(a)(iii), Section 23(a), and
Section 24(a) hereof) in whole or in part upon surrender of the Rights Certificate, with the form of election to purchase and the certificate contained therein duly executed, to the Rights Agent at the principal office or offices of the
Rights Agent designated for such purpose, together with payment of the aggregate Purchase Price with respect to the total number of one one-hundredths of a Preferred Share (or, following the occurrence of a Triggering Event, Common Shares, other
securities, cash, or other assets, as the case may be) as to which such surrendered Rights are then exercisable, at or prior to the earliest of (i) September 20, 2019, (ii) the time at which the Rights are redeemed as provided in Section 23
hereof, or (iii) the time at which the Rights are exchanged in full as provided in Section 24 hereof (the earliest of (i), (ii) and (iii) being herein referred to as the “Expiration Date”). 

 

	 	B.	The definition of “Preferred Shares” contained in Section 1(z) of the Rights Agreement is hereby amended in its entirety and restated to read as follows: 








 (z) “Preferred Shares” shall mean shares of Series A Junior
Participating Preferred Stock, par value $0.001 per share, of the Company having the rights and preferences set forth in the Certificate of Designation attached to this Amendment as Exhibit A, and, to the extent that there are not a
sufficient number of shares of Series A Junior Participating Preferred Stock authorized to permit the full exercise of the Rights, any other series of preferred stock of the Company designated for such purpose containing terms substantially similar
to the terms of the Series A Junior Participating Preferred Stock. 
  

	 	C.	In Exhibit C to the Rights Agreement, all references to “September 20, 2016” are amended and restated in their entirety so that such references read “September 20, 2019.”


  

	2.	Full Force and Effect. Except as expressly amended in this Amendment, the Rights Agreement shall continue in full force and effect unamended and in accordance with the provisions thereof on the date hereof.


  

	3.	Certification. This Section 3 of the Amendment constitutes, for purposes of Section 27 of the Rights Agreement, a certificate from an authorized officer of the Company that (i) this Amendment is in
compliance with the terms of Section 27 of the Rights Agreement, (ii) the Rights remain redeemable at the date of this Amendment, and (iii) this Amendment does not adversely affects the rights, duties or obligations of the Rights Agent under
the Rights Agreement, and (iv) directs the Rights Agent to execute this Amendment. 

  

	4.	Governing Law. This Amendment shall be governed by the laws of the State of Delaware and for all purposes shall be governed by and construed in accordance with the laws of such state applicable to contracts made
and to be performed entirely within such state. 

  

	5.	Effective Date. This Amendment is effective as of September 19, 2016. 

  

	6.	Severability. If any term, provision, covenant or restriction of this Amendment is held by a court of competent jurisdiction to be invalid, void or unenforceable, the remainder of the terms, provisions, covenants
and restrictions of this Amendment shall remain in full force and effect and shall in no way be affected, impaired or invalidated. 

  

	7.	Counterparts. This Amendment may be executed in any number of counterparts, each of which shall be deemed an original, and all of which together shall constitute one and the same instrument. 


(Signature Page Follows) 

  
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 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed as
of the day and year first above written. 
  

			
	CATALYST PHARMACEUTICALS, INC.
		
	By:	 	 /s/ Patrick J. McEnany

		 	Patrick J. McEnany,
		 	Chairman, President and CEO
	
	CONTINENTAL STOCK TRANSFER AND TRUST COMPANY
		
	By:	 	 /s/ Margaret B. Lloyd

	Name:	 	 Margaret B. Lloyd

	Title:	 	 VP




  
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 Exhibit A 

FORM OF 
 CERTIFICATE OF
DESIGNATION, PREFERENCES, AND 
 RIGHTS OF SERIES A JUNIOR PARTICIPATING PREFERRED STOCK 

of 
 CATALYST
PHARMACEUTICALS, INC. 
 Pursuant to Section 151 of the General Corporation Law of the State of Delaware, Catalyst Pharmaceuticals, Inc.
(f/k/a Catalyst Pharmaceutical Partners, Inc.), a corporation organized and existing under the General Corporation Law of the State of Delaware (the “Corporation”), in accordance with the provisions of Section 103 thereof, DOES
HEREBY CERTIFY: 
 That pursuant to the authority conferred upon the Board of Directors by the Amended and Restated Certificate of
Incorporation of the Corporation (as such may be amended, modified or restated from time to time, the “Certificate of Incorporation”), the said Board of Directors effective September 19, 2016, adopted the following resolution
creating a series of Preferred Stock designated as Series A Junior Participating Preferred Stock (as hereinafter defined): 

RESOLVED, that pursuant to the authority vested in the Board of Directors of the Corporation in accordance with the provisions of its
Certificate of Incorporation, a series of Preferred Stock of the Corporation be and it hereby is created, and that the designation and amount thereof and the voting powers, preferences and relative, participating, optional and other special rights
of the shares of such series, and the qualifications, limitations, and restrictions thereof are as follows: 
  

	1.	Designation and Amount. The shares of such series shall be designated as “Series A Junior Participating Preferred Stock” and the number of shares constituting such series
shall be 1,500,000. 

  

	2.	Dividends and Distributions. 

  

	 	A.	 Subject to the prior and superior rights of the holders of any shares of any series of Preferred Stock ranking
prior and superior to the shares of Series A Junior Participating Preferred Stock with respect to dividends, the holders of shares of Series A Junior Participating Preferred Stock, in preference to the holders of shares of Common Stock, par value
$0.001 per share, of the Corporation (the “Common Stock”), and of any other junior stock, shall be entitled to receive, when, as and if declared by the Board of Directors out of funds legally available for the purpose, quarterly
dividends payable in cash on the last day of each fiscal quarter (each such date being referred to herein as a “Quarterly Dividend Payment Date”), commencing on the first Quarterly Dividend Payment Date after the first issuance of a
share or fraction of a share of Series A Junior Participating Preferred Stock, in an amount per share (rounded to the nearest cent) equal to the greater of (a) $1.00 or (b) subject to the provision for adjustment hereinafter set forth, 100




  
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times the aggregate per share amount of all cash dividends, and 100 times the aggregate per share amount (payable in kind) of all non-cash dividends or other distributions, other than a dividend
payable in shares of Common Stock or a subdivision of the outstanding shares of Common Stock (by reclassification or otherwise), declared on the Common Stock since the immediately preceding Quarterly Dividend Payment Date, or, with respect to the
first Quarterly Dividend Payment Date, since the first issuance of any share or fraction of a share of Series A Junior Participating Preferred Stock. In the event the Corporation shall at any time after October 7, 2011 (the “Rights
Dividend Declaration Date”) (i) declare any dividend on Common Stock payable in shares of Common Stock, (ii) subdivide the outstanding Common Stock, or (iii) combine the outstanding Common Stock into a smaller number of shares, then in each
such case the amount to which holders of shares of Series A Junior Participating Preferred Stock were entitled immediately prior to such event under clause (b) of the preceding sentence shall be adjusted by multiplying such amount by a fraction the
numerator of which is the number of shares of Common Stock outstanding immediately after such event and the denominator of which is the number of shares of Common Stock that were outstanding immediately prior to such event. 


 

	 	B.	The Corporation shall declare a dividend or distribution on the Series A Junior Participating Preferred Stock as provided in Paragraph (A) above immediately after it declares a dividend or distribution on the Common
Stock (other than a dividend payable in shares of Common Stock). 

  

	 	C.	Dividends shall begin to accrue and be cumulative on outstanding shares of Series A Junior Participating Preferred Stock from the Quarterly Dividend Payment Date next preceding the date of issue of such shares of
Series A Junior Participating Preferred Stock, unless the date of issue of such shares is prior to the record date for the first Quarterly Dividend Payment Date, in which case dividends on such shares shall begin to accrue from the date of issue of
such shares, or unless the date of issue is a Quarterly Dividend Payment Date or is a date after the record date for the determination of holders of shares of Series A Junior Participating Preferred Stock entitled to receive a quarterly dividend and
before such Quarterly Dividend Payment Date, in either of which events such dividends shall begin to accrue and be cumulative from such Quarterly Dividend Payment Date. Accrued but unpaid dividends shall not bear interest. Dividends paid
on the shares of Series A Junior Participating Preferred Stock in an amount less than the total amount of such dividends at the time accrued and payable on such shares shall be allocated pro rata on a share-by-share basis among all such shares at
the time outstanding. The Board of Directors may fix a record date for the determination of holders of shares of Series A Junior Participating Preferred Stock entitled to receive payment of a dividend or distribution declared thereon, which
record date shall be no more than 30 days prior to the date fixed for the payment thereof. 


  
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	3.	Voting Rights. The holders of shares of Series A Junior Participating Preferred Stock shall have the following voting rights: 


 

	 	A.	Subject to the provision for adjustment hereinafter set forth, each share of Series A Junior Participating Preferred Stock shall entitle the holder thereof to 100 votes on all matters submitted to a vote of the
stockholders of the Corporation. In the event the Corporation shall at any time after the Rights Dividend Declaration Date (i) declare any dividend on Common Stock payable in shares of Common Stock, (ii) subdivide the outstanding Common Stock,
or (iii) combine the outstanding Common Stock into a smaller number of shares, then in each such case the number of votes per share to which holders of shares of Series A Junior Participating Preferred Stock were entitled immediately prior to such
event shall be adjusted by multiplying such number by a fraction, the numerator of which is the number of shares of Common Stock outstanding immediately after such event and the denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event. 

  

	 	B.	Except as otherwise provided herein or by law, the holders of shares of Series A Junior Participating Preferred Stock and the holders of shares of Common Stock shall vote together as one class on all matters submitted
to a vote of stockholders of the Corporation. 

  

	 	C.	     

  

	 	i.	If at any time dividends on any Series A Junior Participating Preferred Stock shall be in arrears in an amount equal to six quarterly dividends thereon, the occurrence of such contingency shall mark the beginning of a
period (herein called a “default period”) that shall extend until such time when all accrued and unpaid dividends for all previous quarterly dividend periods and for the current quarterly dividend period on all shares of Series A
Junior Participating Preferred Stock then outstanding shall have been declared and paid or set apart for payment. During each default period, all holders of Preferred Stock (including holders of the Series A Junior Participating Preferred
Stock) with dividends in arrears in an amount equal to six quarterly dividends thereon, voting as a class, irrespective of series, shall have the right to elect two directors. 


 

	 	ii.	 During any default period, such voting right of the holders of Series A Junior Participating Preferred Stock may
be exercised initially at a special meeting called pursuant to subparagraph (iii) of this Section 3(C) or at any annual meeting of stockholders, and thereafter at annual meetings of stockholders, provided that such voting right shall not be
exercised unless the holders of 10% in number of shares of Preferred Stock outstanding shall be present in person or by proxy. The absence of a quorum of the holders of Common Stock shall not affect the exercise by the holders of Preferred
Stock of such voting right. At any meeting at which the holders of Preferred Stock shall exercise such voting right initially during an existing default period, they shall have the right, voting as a class, to elect directors to fill such
vacancies, if any, in the Board of Directors as may then exist up to two directors or, if such right is exercised at an annual 



  
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meeting, to elect two directors. If the number that may be so elected at any special meeting does not amount to the required number, the holders of Preferred Stock shall have the right to
make such increase in the number of directors as shall be necessary to permit the election by them of the required number. After the holders of Preferred Stock shall have exercised their right to elect directors in any default period and during
the continuance of such period, the number of directors shall not be increased or decreased except by vote of the holders of Preferred Stock as herein provided or pursuant to the rights of any equity securities ranking senior to or pari
passu with the Series A Junior Participating Preferred Stock. 

  

	 	iii.	Unless the holders of Preferred Stock shall, during an existing default period, have previously exercised their right to elect directors, the Board of Directors may order, or any stockholder or stockholders owning in
the aggregate not less than 10% of the total number of shares of Preferred Stock outstanding, irrespective of series, may request, the calling of a special meeting of the holders of Preferred Stock, which meeting shall thereupon be called by the
President, a Vice-President, or the Secretary of the Corporation. Notice of such meeting and of any annual meeting at which holders of Preferred Stock are entitled to vote pursuant to this Paragraph (C)(iii) shall be given to each holder of
record of Preferred Stock by mailing a copy of such notice to such holder at such holder’s last address as the same appears on the books of the Corporation. Such meeting shall be called for a time not earlier than 20 days and not later
than 60 days after such order or request or in default of the calling of such meeting within 60 days after such order or request, such meeting may be called on similar notice by any stockholder or stockholders owning in the aggregate not less than
10% of the total number of shares of Preferred Stock outstanding. Notwithstanding the provisions of this Paragraph (C)(iii), no such special meeting shall be called during the period within 60 days immediately preceding the date fixed for the
next annual meeting of the stockholders. 

  

	 	iv.	During any default period, the holders of Common Stock, and other classes of stock of the Corporation if applicable, shall continue to be entitled to elect the whole number of directors until the holders of Preferred
Stock shall have exercised their right to elect two directors voting as a class, after the exercise of which right (x) the directors so elected by the holders of Preferred Stock shall continue in office until their successors shall have been elected
by such holders or until the expiration of the default period, and (y) any vacancy in the Board of Directors may (except as provided in Paragraph (C)(ii) of this Section 3) be filled by vote of a majority of the remaining directors theretofore
elected by the holders of the class of stock that elected the director whose office shall have become vacant. References in this Paragraph (C) to directors elected by the holders of a particular class of stock shall include directors elected by
such directors to fill vacancies as provided in clause (y) of the foregoing sentence. 


  
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	 	v.	Immediately upon the expiration of a default period, (x) the right of the holders of Preferred Stock as a class to elect directors shall cease, (y) the term of any directors elected by the holders of Preferred Stock as
a class shall terminate, and (z) the number of directors shall be such number as may be provided for in the Certificate of Incorporation or Bylaws irrespective of any increase made pursuant to the provisions of Paragraph (C)(ii) of this Section 3
(such number being subject, however, to change thereafter in any manner provided by law or in the Certificate of Incorporation or Bylaws). Any vacancies in the Board of Directors effected by the provisions of clauses (y) and (z) in the
preceding sentence may be filled by a majority of the remaining directors. 

  

	 	D.	Except as set forth herein, holders of Series A Junior Participating Preferred Stock shall have no special voting rights and their consent shall not be required (except to the extent they are entitled to vote with
holders of Common Stock as set forth herein) for taking any corporate action. 

  

	4.	Certain Restrictions. 

  

	 	A.	Whenever quarterly dividends or other dividends or distributions payable on the Series A Junior Participating Preferred Stock as provided in Section 2 are in arrears, thereafter and until all accrued and unpaid
dividends and distributions, whether or not declared, on shares of Series A Junior Participating Preferred Stock outstanding shall have been paid in full, the Corporation shall not: 


 

	 	i.	declare or pay dividends on, or make any other distributions on, any shares of stock ranking junior (either as to dividends or upon liquidation, dissolution, or winding up) to the Series A Junior Participating Preferred
Stock; 

  

	 	ii.	declare or pay dividends on, or make any other distributions on, any shares of stock ranking on a parity (either as to dividends or upon liquidation, dissolution, or winding up) with the Series A Junior Participating
Preferred Stock, except dividends paid ratably on the Series A Junior Participating Preferred Stock and all such parity stock on which dividends are payable or in arrears in proportion to the total amounts to which the holders of all such shares are
then entitled; 

  

	 	iii.	redeem or purchase or otherwise acquire for consideration shares of any stock ranking junior (either as to dividends or upon liquidation, dissolution, or winding up) to the Series A Junior Participating Preferred Stock,
provided that the Corporation may at any time redeem, purchase, or otherwise acquire shares of any such junior stock in exchange for shares of any stock of the Corporation ranking junior (either as to dividends or upon dissolution,
liquidation, or winding up) to the Series A Junior Participating Preferred Stock; or 


  
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	 	iv.	redeem or purchase or otherwise acquire for consideration any shares of Series A Junior Participating Preferred Stock, or any shares of stock ranking on a parity with the Series A Junior Participating Preferred Stock,
except in accordance with a purchase offer made in writing or by publication (as determined by the Board of Directors) to all holders of such shares upon such terms as the Board of Directors, after consideration of the respective annual dividend
rates and other relative rights and preferences of the respective series and classes, shall determine in good faith will result in fair and equitable treatment among the respective series or classes. 


 

	 	B.	The Corporation shall not permit any subsidiary of the Corporation to purchase or otherwise acquire for consideration any shares of stock of the Corporation unless the Corporation could, under Paragraph (A) of this
Section 4, purchase or otherwise acquire such shares at such time and in such manner. 

  

	5.	Reacquired Shares. Any shares of Series A Junior Participating Preferred Stock purchased or otherwise acquired by the Corporation in any manner whatsoever shall be retired and cancelled promptly after the
acquisition thereof. All such shares shall upon their cancellation become authorized but unissued shares of Preferred Stock and may be reissued as part of a new series of Preferred Stock to be created by resolution or resolutions of the Board
of Directors, subject to the conditions and restrictions on issuance set forth herein, in the Certificate of Incorporation, or in any other Certificate of Designation creating a series of Preferred Stock or any similar stock, or as otherwise
required by law. 

  

	6.	Liquidation, Dissolution, or Winding Up. 

  

	 	A.	 Upon any liquidation (voluntary or otherwise), dissolution, or winding up of the Corporation, no distribution
shall be made to the holders of shares of stock ranking junior (either as to dividends or upon liquidation, dissolution, or winding up) to the Series A Junior Participating Preferred Stock unless, prior thereto, the holders of shares of Series A
Junior Participating Preferred Stock shall have received an amount equal to $100 per share of Series A Participating Preferred Stock, plus an amount equal to accrued and unpaid dividends and distributions thereon, whether or not declared, to the
date of such payment (the “Series A Liquidation Preference”). Following the payment of the full amount of the Series A Liquidation Preference, no additional distributions shall be made to the holders of shares of Series A
Junior Participating Preferred Stock unless, prior thereto, the holders of shares of Common Stock shall have received an amount per share (the “Common Adjustment”) equal to the quotient obtained by dividing (i) the Series A
Liquidation Preference by (ii) 100 (as appropriately adjusted as set forth in subparagraph (C) below to reflect such events as stock splits, stock dividends, and recapitalizations with respect to the Common Stock) (such number in clause (ii),




  
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the “Adjustment Number”). Following the payment of the full amount of the Series A Liquidation Preference and the Common Adjustment in respect of all outstanding shares of
Series A Junior Participating Preferred Stock and Common Stock, respectively, holders of Series A Junior Participating Preferred Stock and holders of shares of Common Stock shall receive their ratable and proportionate share of the remaining assets
to be distributed in the ratio of the Adjustment Number to one with respect to such Preferred Stock and Common Stock, on a per share basis, respectively. 

  

	 	B.	In the event, however, that there are not sufficient assets available to permit payment in full of the Series A Liquidation Preference and the liquidation preferences of all other series of preferred stock, if any,
which rank on a parity with the Series A Junior Participating Preferred Stock, then such remaining assets shall be distributed ratably to the holders of such parity shares in proportion to their respective liquidation preferences. 


 

	 	C.	In the event the Corporation shall at any time after the Rights Dividend Declaration Date (i) declare any dividend on Common Stock payable in shares of Common Stock, (ii) subdivide the outstanding Common Stock, or (iii)
combine the outstanding Common Stock into a smaller number of shares, then in each such case the Adjustment Number in effect immediately prior to such event shall be adjusted by multiplying such Adjustment Number by a fraction, the numerator of
which is the number of shares of Common Stock outstanding immediately after such event and the denominator of which is the number of shares of Common Stock that were outstanding immediately prior to such event. 


 

	7.	Consolidation, Merger, etc. In case the Corporation shall enter into any consolidation, merger, combination, or other transaction in which the shares of Common Stock are exchanged for or changed into other
stock or securities, cash, or any other property, then in any such case the shares of Series A Junior Participating Preferred Stock shall at the same time be similarly exchanged or changed in an amount per share (subject to the provision for
adjustment hereinafter set forth) equal to 100 times the aggregate amount of stock, securities, cash, or any other property (payable in kind), as the case may be, into which or for which each share of Common Stock is changed or exchanged. In
the event the Corporation shall at any time after the Rights Dividend Declaration Date (i) declare any dividend on Common Stock payable in shares of Common Stock, (ii) subdivide the outstanding Common Stock, or (iii) combine the outstanding Common
Stock into a smaller number of shares, then in each such case the amount set forth in the preceding sentence with respect to the exchange or change of shares of Series A Junior Participating Preferred Stock shall be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Common Stock outstanding immediately after such event and the denominator of which is the number of shares of Common Stock that were outstanding immediately prior to such event.


  

	8.	No Redemption. The shares of Series A Junior Participating Preferred Stock shall not be redeemable. 


  
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	9.	Ranking. The Series A Junior Participating Preferred Stock shall rank junior to all other series of the Corporation’s Preferred Stock as to the payment of dividends and the distribution of assets,
unless the terms of any such series shall provide otherwise. 

  

	10.	Amendment. At any time when any shares of Series A Junior Participating Preferred Stock are outstanding, neither the Certificate of Incorporation of the Corporation nor this Certificate of Designation shall
be amended in any manner that would materially alter or change the powers, preferences, or special rights of the Series A Junior Participating Preferred Stock so as to affect them adversely without the affirmative vote of the holders of two-thirds
or more of the outstanding shares of Series A Junior Participating Preferred Stock, voting separately as a class. 

  

	11.	Fractional Shares. The Series A Junior Participating Preferred Stock may be issued in fractions of a share that shall entitle the holder, in proportion to such holder’s fractional shares, to exercise
voting rights, receive dividends, participate in distributions, and to have the benefit of all other rights of holders of Series A Junior Participating Preferred Stock. 


(Signature Page Follows) 

  
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 IN WITNESS WHEREOF, Catalyst Pharmaceuticals, Inc. has caused this Certificate of
Designation to be signed by the undersigned this      day of September, 2016. 
  

			
	 CATALYST PHARMACEUTICALS, INC.

		
	BY:	 	  

		 	Patrick J. McEnany
		 	Chairman, President and CEO



  
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