Sec Form 4 Filing - Freund John Gordon @ SI-BONE, Inc. - 2021-06-10

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 Freund John Gordon 2. Issuer Name and Ticker or Trading Symbol SI-BONE, Inc. [ SIBN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O SKYLINE VENTURES, 525 UNIVERSITY AVENUE, SUITE 1350 3. Date of Earliest Transaction (MM/DD/YY) 06/10/2021 (Street) PALO ALTO, CA94301 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 Common Stock 06/10/2021 A 3,848 ( 1 ) A $ 0 12,645 ( 2 ) D Common Stock 100,750 I By John Freund Family Partnership IV, L.P ( 3 ) Common Stock 383,458 I Skyline Venture Partners V, L.P. ( 4 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Freund John Gordon C/O SKYLINE VENTURES 525 UNIVERSITY AVENUE, SUITE 1350 PALO ALTO, CA94301 X Signatures /s/ Michael A. Pisetsky, Attorney-in-Fact for John G. Freund 06/14/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Reflects shares issuable on the settlement of restricted stock units granted to the Reporting Person. Each restricted stock unit represents acontingent right to receive one share of the Issuer's common stock. The shares subject to the restricted stock unit will be vesting 100% uponthe earlier of (i) the next annual general meeting of the stockholders of the Company or (ii) the date one year from the VestingCommencement Date, subject to the Reporting Person's continuous service as a member of the Company's Board of Directors until suchdate. ( 2 )Includes 3,848 shares issuable on the settlement of restricted stock units granted to the Reporting Person. Each restricted stock unitrepresents a contingent right to receive one share of the Issuer's common stock. ( 3 )Shares held by John Freund Family Partnership IV, L.P. ("Family LP"). Reporting Person, a member of Issuer's board of directors, is a generalpartner of Family LP and may be deemed to have voting and investment power with respect to the securities held by Family LP. ReportingPerson disclaims beneficial ownership of such securities, except to the extent of his pecuniary interest therein. ( 4 )Shares held by SVP V. Skyline Venture Management V, LLC ("LLC") is the general partner of SVP V and as such may be deemed to havevoting and investment power with respect to the securities of SVP V. Reporting Person, a member of Issuer's board of directors, is a managing director of LLC and may be deemed to have voting and investment power with respect to the securities held by SVP V. Reporting Person disclaims beneficial ownership of such securities, except to the extent of his 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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