Sec Form 4 Filing - Mayfield XIII, a Cayman Islands Exempted Limited Partnership @ Couchbase, Inc. - 2021-07-26

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 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

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1. Name and Address of Reporting Person Mayfield XIII, a Cayman Islands Exempted Limited Partnership 2. Issuer Name and Ticker or Trading Symbol Couchbase, Inc. [ BASE] 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) 2484 SAND HILL ROAD 3. Date of Earliest Transaction (MM/DD/YY) 07/26/2021 (Street) MENLO PARK, CA94025 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 Common Stock 07/26/2021 C 3,251,435 A 3,341,480 I Mayfield XIII, a Cayman Islands Exempted Limited Partnership ( 2 )

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 Series B Preferred Stock ( 1 ) 07/26/2021 C 1,909,090 ( 1 ) ( 1 ) Common Stock 1,909,090 $ 0 0 I Mayfield XIII, a Cayman Islands Exempted Limited Partnership ( 2 ) Series C Preferred Stock ( 1 ) 07/26/2021 C 715,278 ( 1 ) ( 1 ) Common Stock 715,278 $ 0 0 I Mayfield XIII, a Cayman Islands Exempted Limited Partnership ( 2 ) Series D Preferred Stock ( 1 ) 07/26/2021 C 258,017 ( 1 ) ( 1 ) Common Stock 258,017 $ 0 0 I Mayfield XIII, a Cayman Islands Exempted Limited Partnership ( 2 ) Series E Preferred Stock ( 1 ) 07/26/2021 C 120,645 ( 1 ) ( 1 ) Common Stock 127,014 $ 0 0 I Mayfield XIII, a Cayman Islands Exempted Limited Partnership ( 2 ) Series F Preferred Stock ( 1 ) 07/26/2021 C 169,212 ( 1 ) ( 1 ) Common Stock 169,212 $ 0 0 I Mayfield XIII, a Cayman Islands Exempted Limited Partnership ( 2 ) Series G Preferred Stock ( 1 ) 07/26/2021 C 68,269 ( 1 ) ( 1 ) Common Stock 72,824 $ 0 0 I Mayfield XIII, a Cayman Islands Exempted Limited Partnership ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Mayfield XIII, a Cayman Islands Exempted Limited Partnership 2484 SAND HILL ROAD MENLO PARK, CA94025 X Mayfield XIII Management (EGP), L.P., a Cayman Islands Exempted Limited Partnership C/O MAYFIELD, 2484 SAND HILL ROAD MENLO PARK94025 X Mayfield XIII Management (UGP), Ltd., a Cayman Islands Exempted Co. C/O MAYFIELD, 2484 SAND HILL ROAD MENLO PARK, CA94025 X Signatures Mayfield XIII, a Cayman Islands Exempted Limited Partnership, By: Mayfield XIII Management (EGP), L.P., its general partner, By: Mayfield XIII Management (UGP), Ltd., its general partner, By: /s/ Paul Kohli, Authorized Signatory 07/26/2021 Signature of Reporting Person Date Mayfield XIII Management (EGP), L.P., By: Mayfield XIII Management (UGP), Ltd., its general partner, By: /s/ Paul Kohli, Authorized Signatory 07/26/2021 Signature of Reporting Person Date Mayfield XIII Management (UGP), Ltd., By: /s/ Paul Kohli, Authorized Signatory 07/26/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Immediately prior to the closing of the Issuer's initial public offering, each share of Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, and Series F Preferred Stock automatically converted into shares of the Issuer's Common Stock on a one-for-one basis, each share of Series E Preferred Stock automatically converted into shares of the Issuer's Common Stock on a 1.05279880234039-for-one basis, and each share of Series G Preferred Stock automatically converted into shares of the Issuer's Common Stock on a 1.06673317089756 basis. The preferred stock has no expiration date. ( 2 )These shares are held of record by Mayfield XIII, a Cayman Islands Exempted Limited Partnership, or MF XIII. Mayfield XIII Management (UGP), Ltd., a Cayman Islands Exempted Company, or MF XIII UGP, is the general partner of Mayfield XIII Management (EGP), L.P., a Cayman Islands Exempted Limited Partnership, which is the general partner of MF XIII. Rajeev Batra, Navin Chaddha and Vaneeta Varma are the directors of MF XIII UGP. As a result, each of the foregoing entities and individuals may be deemed to share beneficial ownership of the shares owned by MF XIII, but each such entity or person disclaims such beneficial ownership except to the extent of its or their pecuniary interest therein.

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).

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