FORM 4
[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         	UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
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                      	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	                      	

1. Name and Address of Reporting Person *

WELLCOME TRUST LTD (THE) as trustee of the WELLCOME TRUST	2. Issuer Name and Ticker or Trading Symbol

CASTLIGHT HEALTH, INC. [ CSLT ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable)

_____ Director                      __ X __ 10% Owner
_____ Officer (give title below)      _____ Other (specify below)	
(Last)          (First)          (Middle)

215 EUSTON ROAD	3. Date of Earliest Transaction (MM/DD/YYYY)

3/19/2014		
(Street)

LONDON, X0 NW1 2BE
(City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)

 	6. Individual or Joint/Group Filing (Check Applicable Line)

_ X _ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person	

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned	
1.Title of Security
(Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code
(Instr. 8)	4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)	5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)	
			Code	V	Amount	(A) or (D)	Price				

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)	
1. Title of Derivate Security
(Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code
(Instr. 8)	5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)	6. Date Exercisable and Expiration Date	7. Title and Amount of Securities Underlying Derivative Security
(Instr. 3 and 4)	8. Price of Derivative Security
(Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)	
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares					
Series A Convertible Preferred Stock  	$0   (1)	3/19/2014  	 	C  	  	  	345881   	  (1)	  (1)	Class A Common Stock   (2) (3)	345881  	$0  	0  	D  	 	
Series A-1 Convertible Preferred Stock  	$0   (1)	3/19/2014  	 	C  	  	  	135931   	  (1)	  (1)	Class A Common Stock   (2) (3)	135931  	$0  	0  	D  	 	
Series C Convertible Preferred Stock  	$0   (1)	3/19/2014  	 	C  	  	  	4378380   	  (1)	  (1)	Class A Common Stock   (2) (3)	4378380  	$0  	0  	D  	 	
Series D Convertible Preferred Stock  	$0   (1)	3/19/2014  	 	C  	  	  	1656572   	  (1)	  (1)	Class A Common Stock   (2) (3)	1656572  	$0  	0  	D  	 	
Class A Common Stock  	$0   (2) (3)	3/19/2014  	 	C  	  	6516764   (1)  	  	  (2) (3)	  (2) (3)	Class B Common Stock   (3)	6516764  	$0  	6568646  	D  	 	

Explanation of Responses:	
(  1) 	In connection with the closing of the Issuer's initial public offering (the "IPO") on March 19, 2014, each share of Convertible Preferred Stock automatically converted into one (1) share of Class A Common Stock for no additional consideration. All shares of Class A Common Stock issued upon conversion were aggregated.	
(  2) 	Each share of Class A Common Stock is convertible, at any time at the option of the holder, into one (1) share of Class B Common Stock. In addition, each share of Class A Common Stock will convert automatically into one (1) share of Class B Common Stock upon the transfer, whether or not for value, that occurs after the closing of the IPO to any transferee who is not a "Permitted Transferee", as defined in the Issuer's Restated Certificate of Incorporation in effect as of the date hereof. The shares of Class A Common Stock have no expiration date.	
(  3) 	Each share of the Issuer's Class A Common Stock will convert automatically into one (1) share of Class B Common Stock upon the earliest to occur of the following: (a) the first date on which the number of shares of Class A Common Stock then outstanding is less than 15,340,384 shares, (b) March 19, 2024, or (c) a time and date approved in writing by holders of at least a majority of the then-outstanding shares of Class A Common Stock. The shares of Class A Common Stock and Class B Common Stock have no expiration date.	

Reporting Owners	
Reporting Owner Name / Address	Relationships	
	Director	10% Owner	Officer	Other	
WELLCOME TRUST LTD (THE) as trustee of the WELLCOME TRUST
215 EUSTON ROAD
LONDON, X0 NW1 2BE		X			

Signatures		
/s/ Nicholas Moakes, Managing Director, Investments Division		3/19/2014	
** Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.	
*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).	
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).	
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.	
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