SEC Form 4 
FORM 4	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
or Section 30(h) of the Investment Company Act of 1940 	  
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	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).			
1. Name and Address of Reporting Person*
Skyline Venture Partners V LP	

(Last)	(First)	(Middle)	
525 UNIVERSITY AVENUE, SUITE 1350	

(Street) 
PALO ALTO	CA	94301	

(City)	(State)	(Zip)	
	2. Issuer Name and Ticker or Trading Symbol 
SI-BONE, Inc. [ SIBN ] 	5. Relationship of Reporting Person(s) to Issuer 
(Check all applicable) 
	Director	X	10% Owner	
	Officer (give title below)		Other (specify below)	

	3. Date of Earliest Transaction (Month/Day/Year)
08/26/2019 		
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) 
	Form filed by One Reporting Person	
X	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. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	08/26/2019		S		152,424	D	$18.4038(1) 	3,819,985	I	By Skyline Venture Partners V, L.P(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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)	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: 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					
1. Name and Address of Reporting Person*
Skyline Venture Partners V LP	

(Last)	(First)	(Middle)	
525 UNIVERSITY AVENUE, SUITE 1350	

(Street) 
PALO ALTO	CA	94301	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
Skyline Venture Management V, LLC	

(Last)	(First)	(Middle)	
525 UNIVERSITY AVENUE, SUITE 1350	

(Street) 
PALO ALTO	CA	94301	

(City)	(State)	(Zip)	
	
Explanation of Responses:	
1. The price reported in column 4 is a weighted-average price. The shares were sold in multiple transactions ranging from $18.40 to $19.21, inclusive. The Reporting Person undertakes to provide the Issuer, any securityholder of the Issuer, or the Staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.	
2. Shares held by Skyline Venture Partners V, L.P. ("SVP V"). Skyline Venture Management V, LLC ("LLC") is the general partner of SVP V and as such may be deemed to have voting and investment power with respect to the securities of SVP V. Dr. Freund, a member of the Issuer's board of directors, together with Yasunori Kaneko, are the managing directors of LLC and each may be deemed to have voting and investment power with respect to the securities held by SVP V. Dr. Freund and Mr. Kaneko disclaim beneficial ownership of such securities, except to the extent of their pecuniary interest therein.	
Remarks:	
	
	Skyline Venture Partners V, L.P.	08/27/2019	
	Skyline Venture Management V, LLC, By: /s/ Michael A. Pisetsky, Attorney-in-Fact	08/27/2019	
	** 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.	
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.	
POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and
appoints each of LAURA A. FRANCIS, MICHAEL A. PISETSKY,
MATTHEW B. HEMINGTON and JOHN T. MCKENNA, signin
individually, the undersigned's true and lawful attorneys-in fact
and agents to:

(1)     execute for and on behalf of the undersigned,
in the undersigned's capacity as an officer, director
or beneficial owner of more than 10% of a registered
class of securities of SI-BONE, INC. (the "Company"),
Forms 3, 4 and 5 (including any amendments thereto)
in accordance with Section 16(a) of the Securities
Exchange Act of 1934, as amended (the "Exchange Act")
and the rules thereunder and a Form ID, Uniform Application
for Access Codes to File on EDGAR;
(2) do and perform any and all acts for and on behalf of
the undersigned that may be necessary or desirable to execute
such Forms 3, 4 or 5 or Form ID (including any amendments thereto)
and timely file such forms with the United States Securities and
Exchange Commission and any stock exchange or similar authority;
and
(3) take any other action of any nature whatsoever in connection
with the foregoing which, in the opinion of such attorney-in-fact,
may be of benefit, in the best interest of, or legally required by,
the undersigned, it being understood that the documents executed by
such attorney-in-fact on behalf of the undersigned pursuant to this
Power of Attorney shall be in such form and shall contain such terms
and conditions as such attorney-in-fact may approve in such
attorney-in-fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full
power and authority to do and perform any and every act and thing
whatsoever requisite, necessary or proper to be done in the
exercise of any of the rights and powers herein granted,
as fully to all intents and purposes as the undersigned might
or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming
all that such attorney-in-fact, or such attorney-in-fact's
substitute or substitutes, shall lawfully do or cause to be
done by virtue of this power of attorney and the rights and
powers herein granted. The undersigned acknowledges that the
foregoing attorneys-in-fact, in serving in such capacity at
the request of the undersigned, are not assuming, nor is the
Company assuming, any of the undersigned's responsibilities to
comply with Section 16 of the Exchange Act.

This Power of Attorney shall remain in full force and effect
until the earliest to occur of (a) the undersigned is no longer
required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued
by the Company, (b) revocation by the undersigned in a signed
writing delivered to the foregoing attorneys-in-fact or (c)
as to any attorney-in-fact individually, until such
attorney-in-fact is no longer employed by the Company
or Cooley LLP.

IN WITNESS WHEREOF, the undersigned has caused this
Power of Attorney to be executed as of August 13, 2019.

SKYLINE VENTURE PARTNERS V, L.P.
By: Skyline Venture Management V, LLC
Its: General Partner
By: /s/John G. Freund-Managing Director

SKYLINE VENTURE MANAGEMENT V, LLC
By:/s/John G. Freund-Managing Member