Sec Form 3 Filing - Cook Joseph C. III @ CASTLE BIOSCIENCES INC - 2019-07-24

FORM 3 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 Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person Cook Joseph C. III 2. Issuer Name and Ticker or Trading Symbol CASTLE BIOSCIENCES INC [ CSTL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O CASTLE BIOSCIENCES, INC., 820 S. FRIENDSWOOD DRIVE, SUITE 201 3. Date of Earliest Transaction (MM/DD/YY) 07/24/2019 (Street) FRIENDSWOOD, TX77546 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction 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 Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 Stock option (right to buy) $ 16 ( 1 ) 07/23/2029 Common Stock 30,895 D Series A Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 16,015 I By L.P. ( 3 ) Series B Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 100,210 D Series D Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 13,058 D Series D Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 277,074 I By L.P. ( 3 ) Series E-1 Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 380,190 I By L.P. ( 3 ) Series E-2 Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 4,479 D Series E-2 Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 129,925 I By L.P. ( 3 ) Series E-3 Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 3,840 D Series E-3 Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 117,180 I By L.P. ( 3 ) Series F Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 47,495 D Series F Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 416,537 I By L.P. ( 3 ) Convertible Promissory Note ( 4 ) ( 4 ) ( 4 ) Common Stock $ 205,970.51 ( 4 ) D Convertible Promissory Note ( 5 ) ( 5 ) ( 5 ) Common Stock $ 1,200,000 ( 5 ) I By L.P. ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Cook Joseph C. III C/O CASTLE BIOSCIENCES, INC. 820 S. FRIENDSWOOD DRIVE, SUITE 201 FRIENDSWOOD, TX77546 X X Signatures /s/ Greg Acosta, Attorney-in-fact 07/24/2019 Signature of Reporting Person Date

Explanation of Responses:

( 1 )25% of the shares shall vest on August 1, 2020, and the remaining shares shall vest in 36 equal monthly installments thereafter. ( 2 )All outstanding shares of Preferred Stock will automatically convert into shares of Common Stock immediately upon the closing of the Issuer's initial public offering (the "IPO"), for no additional consideration at a rate of 1 share of Common Stock for each 1.219 shares of Preferred Stock,based on the conversion price currently in effect. The Preferred Stock has no expiration date. ( 3 )Held by MGC Venture Partners 2013, L.P. (the "L.P."). MGC Venture Partners 2013 GP, LLC (the "LLC") is the general partner of the L.P. The Reporting Person is a managing director of the LLC and shares voting and investment power over the shares held by the L.P. ( 4 )The principal amount of the Convertible Promissory Note held by the designated Reporting Person is $205,970.51. Upon closing of the IPO, all unpaid principal and accrued interest outstanding on the Convertible Promissory Note (the "Conversion Amount") will automatically convert into the number of shares of Common Stock that is equal to the Conversion Amount as of the closing date divided by 80% of the IPO price per share. ( 5 )The principal amount of the Convertible Promissory Note held by the L.P. is $1,200,000.00. Upon closing of the IPO, the Conversion Amount will automatically convert into the number of shares of Common Stock that is equal to the Conversion Amount as of the closing date divided by 80% of the IPO price per share.

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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.