Key facts
- This page summarizes ARCH Venture Fund IX, L.P.'s Form 4 filing for Boundless Bio, Inc. (BOLD).
- 3 reported transactions and 8 derivative rows are listed below.
- Accepted by SEC: 06 Jul 2026, 17:43.
ARCH Venture Fund IX, L.P. - 01 Jul 2026 Form 4 Insider Report for Boundless Bio, Inc. (BOLD)
- Reporting relationship
- 10%+ Owner
- Issuer ticker
- BOLD
- Reported as of
- 01 Jul 2026
- Net transaction value
- -$39,840
- SEC form
- 4
- Accepted by SEC
- 06 Jul 2026, 17:43:19 UTC
- Prior SEC filing
- 04 Apr 2024
- Source filing
- View source filing
- Reporting owner signature
- /s/ ARCH Venture Fund X Overage, L.P., By: ARCH Venture Partners X Overage, L.P., its General Partner, By: ARCH Venture Partners X, LLC, its General Partner, By: Mark McDonnell, attorney in-fact
Source evidence
Original filing metadata and source links for verification.
4 source fields
Reporting owner
1 detail
Key filing fact
ARCH Venture Fund IX, L.P. filed Form 4 for Boundless Bio, Inc. (BOLD) on 06 Jul 2026.
Change
- Previous filing in this sequence was filed on 04 Apr 2024.
- Current net transaction value: -$39,840.
Research use
- This tells you what this filing adds before you inspect full transaction and derivative tables.
- You can trace every row back to the original SEC filing document.
Evidence
Filed on Form 4
View source filing
Ownership activity is grounded in SEC Form 4 disclosures.
Reporting Owners (8)
CIK 0001666306
Primary reporting owner
ARCH Venture Fund IX, L.P.
- Relationship
- 10%+ Owner
- Address
- 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
- Signature
- /s/ ARCH Venture Fund X Overage, L.P., By: ARCH Venture Partners X Overage, L.P., its General Partner, By: ARCH Venture Partners X, LLC, its General Partner, By: Mark McDonnell, attorney in-fact
- Signature date
- 06 Jul 2026
CIK 0001666307
ARCH Venture Fund IX Overage, L.P.
- Relationship
- 10%+ Owner
- Address
- 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
- Signature
- /s/ ARCH Venture Fund IX, L.P., By: ARCH Venture Partners IX, L.P., its General Partner, By: ARCH Venture Partners IX, LLC, its General Partner, By: Mark McDonnell, attorney in-fact
- Signature date
- 06 Jul 2026
CIK 0001757017
ARCH Venture Fund X Overage, L.P.
- Relationship
- 10%+ Owner
- Address
- 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
- Signature
- /s/ ARCH Venture Fund IX Overage, L.P., By: ARCH Venture Partners IX Overage, L.P., its General Partner, By: ARCH Venture Partners IX, LLC, its General Partner, By: Mark McDonnell attorney in-fact
- Signature date
- 06 Jul 2026
CIK 0001723173
ARCH Venture Partners IX, L.P.
- Relationship
- 10%+ Owner
- Address
- 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
- Signature
- /s/ ARCH Venture Partners X Overage, L.P. By: ARCH Venture Partners X, LLC, its General Partner, By: Mark McDonnell, attorney in-fact
- Signature date
- 06 Jul 2026
CIK 0001723172
ARCH Venture Partners IX Overage, L.P.
- Relationship
- 10%+ Owner
- Address
- 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
- Signature
- /s/ ARCH Venture Partners X, LLC, By: Mark McDonnell, attorney in-fact
- Signature date
- 06 Jul 2026
CIK 0001768905
ARCH Venture Partners X Overage, L.P.
- Relationship
- 10%+ Owner
- Address
- 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
- Signature
- /s/ ARCH Venture Partners IX, L.P., By: ARCH Venture Partners IX, LLC, its General Partner, By: Mark McDonnell, attorney in-fact
- Signature date
- 06 Jul 2026
CIK 0001723174
ARCH Venture Partners IX, LLC
- Relationship
- 10%+ Owner
- Address
- 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
- Signature
- /s/ ARCH Venture Partners IX Overage, L.P., By: ARCH Venture Partners IX, LLC, its General Partner, By: Mark McDonnell, attorney in-fact
- Signature date
- 06 Jul 2026
CIK 0001769012
ARCH Venture Partners X, LLC
- Relationship
- 10%+ Owner
- Address
- 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
- Signature
- /s/ ARCH Venture Partners IX, LLC, By: Mark McDonnell, attorney in-fact
- Signature date
- 06 Jul 2026
Reported non-derivative transactions
Shares, units, or other non-derivative securities reported in this filing.
BOLD
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,000
- Change %
- Price
- $1.03*
- Shares after
- 16,000
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,000
- Change %
- Price
- $1.03*
- Shares after
- 16,000
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,000
- Change %
- Price
- $1.03*
- Shares after
- 16,000
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,000
- Change %
- Price
- $1.03*
- Shares after
- 16,000
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,000
- Change %
- Price
- $1.03*
- Shares after
- 16,000
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,000
- Change %
- Price
- $1.03*
- Shares after
- 16,000
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,000
- Change %
- Price
- $1.03*
- Shares after
- 16,000
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,000
- Change %
- Price
- $1.03*
- Shares after
- 16,000
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Sale
- Transaction value
- $39,840
- Shares
- -16,000
- Change %
- -100%
- Price
- $2.49
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Sale
- Transaction value
- $39,840
- Shares
- -16,000
- Change %
- -100%
- Price
- $2.49
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Sale
- Transaction value
- $39,840
- Shares
- -16,000
- Change %
- -100%
- Price
- $2.49
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Sale
- Transaction value
- $39,840
- Shares
- -16,000
- Change %
- -100%
- Price
- $2.49
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Sale
- Transaction value
- $39,840
- Shares
- -16,000
- Change %
- -100%
- Price
- $2.49
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Sale
- Transaction value
- $39,840
- Shares
- -16,000
- Change %
- -100%
- Price
- $2.49
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Sale
- Transaction value
- $39,840
- Shares
- -16,000
- Change %
- -100%
- Price
- $2.49
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
transaction
Common Stock
Sale
- Transaction value
- $39,840
- Shares
- -16,000
- Change %
- -100%
- Price
- $2.49
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Footnotes
- F1
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 683,759
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F2, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 683,759
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F2, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 683,759
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F2, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 683,759
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F2, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 683,759
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F2, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 683,759
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F2, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 683,759
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F2, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 683,759
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F2, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 828,570
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F3, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 828,570
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F3, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 828,570
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F3, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 828,570
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F3, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 828,570
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F3, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 828,570
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F3, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 828,570
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F3, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 828,570
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F3, F4
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,181,766
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F5, F6
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,181,766
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F5, F6
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,181,766
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F5, F6
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,181,766
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F5, F6
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,181,766
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F5, F6
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,181,766
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F5, F6
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,181,766
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F5, F6
BOLD
holding
Common Stock
No transaction description listed
- Transaction value
- Shares
- Change %
- Price
- Shares after
- 1,181,766
- Date
- 01 Jul 2026
- Ownership
- See footnotes
- Footnotes
- F5, F6
Reported derivative securities
Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.
BOLD
transaction
Derivative
Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -16,000
- Change %
- -100%
- Price
- $0.000000*
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $1.03
- Footnotes
- F1, F7
BOLD
transaction
Derivative
Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -16,000
- Change %
- -100%
- Price
- $0.000000*
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $1.03
- Footnotes
- F1, F7
BOLD
transaction
Derivative
Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -16,000
- Change %
- -100%
- Price
- $0.000000*
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $1.03
- Footnotes
- F1, F7
BOLD
transaction
Derivative
Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -16,000
- Change %
- -100%
- Price
- $0.000000*
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $1.03
- Footnotes
- F1, F7
BOLD
transaction
Derivative
Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -16,000
- Change %
- -100%
- Price
- $0.000000*
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $1.03
- Footnotes
- F1, F7
BOLD
transaction
Derivative
Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -16,000
- Change %
- -100%
- Price
- $0.000000*
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $1.03
- Footnotes
- F1, F7
BOLD
transaction
Derivative
Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -16,000
- Change %
- -100%
- Price
- $0.000000*
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $1.03
- Footnotes
- F1, F7
BOLD
transaction
Derivative
Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -16,000
- Change %
- -100%
- Price
- $0.000000*
- Shares after
- 0
- Date
- 01 Jul 2026
- Ownership
- See footnote
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $1.03
- Footnotes
- F1, F7
* marks a reported price that did not pass the local price check.
Additional SEC filing notes
Filing notes and footnotes
Explanation of responses 7 footnotes
Footnote F1
Represents a cashless stock option exercise by Kristina Burow. The net proceeds of such exercise were remitted to ARCH Venture Fund IX, L.P. (ARCH IX), ARCH Venture Fund IX Overage, L.P. (ARCH IX Overage), and ARCH Venture Fund X, L.P. (AVF X Overage LP). The stock option was granted to Kristina Burow in connection with her service on the board of directors of the Issuer.
Footnote F2
Represents shares held directly by ARCH Venture Fund IX, L.P. (ARCH IX). ARCH Venture Partners IX, L.P. (AVP IX LP) is the sole general partner of ARCH IX.
Footnote F3
Represents shares held directly by ARCH Venture Fund IX Overage, L.P. (ARCH IX Overage). ARCH Venture Partners IX Overage, L.P. (AVP IX Overage LP) is the sole general partner of ARCH IX Overage.
Footnote F4
ARCH Venture Partners IX, LLC (AVP IX LLC) is the sole general partner of each of AVP IX LP and AVP IX Overage LP. Keith Crandell, Robert Nelsen and Clinton Bybee are managing directors of AVP IX LLC (the AVP IX MDs). AVP IX LP and AVP IX Overage LP may be deemed to beneficially own the shares held by ARCH IX and ARCH IX Overage, respectively, AVP IX LLC may be deemed to beneficially own the shares held by ARCH IX and ARCH IX Overage, and each of the AVP IX MDs may be deemed to share the power to direct the disposition and vote of the shares held by ARCH IX and ARCH IX Overage. AVP IX LP, AVP IX Overage LP, AVP IX LLC, and the AVP IX MDs each disclaim beneficial ownership except to to the extent of any pecuniary interest therein, if any.
Footnote F5
Represents shares held directly by ARCH Venture Fund X Overage, L.P. (ARCH X Overage). ARCH Venture Partners X Overage, L.P. (AVP X Overage LP) is the sole general partner of ARCH X Overage.
Footnote F6
ARCH Venture Partners X, LLC (AVP X LLC) is the sole general partner of AVP X Overage LP. Keith Crandell, Robert Nelsen, Kristina Burow and Steven Gillis are members of the investment committee of AVP X LLC (the AVP X Committee Members). AVP X Overage LP may be deemed to beneficially own the shares held by ARCH X Overage, AVP X LLC may be deemed to beneficially own the shares held by ARCH X Overage, and each of the AVP X Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH X Overage. AVP X Overage LP, AVP X LLC, and the AVP X Committee Members each disclaim beneficial ownership except to the extent of any pecuniary interest therein, if any.
Footnote F7
The stock option vested in substantially equal monthly installments over the 11 months following June 23, 2025. The final unvested portion vested on June 15, 2026, the date of the Issuer's 2026 annual meeting of stockholders.
SEC remarks
This Form 4 is one of two reports relating to the same transaction being filed jointly by ARCH IX, AVP IX LP, ARCH IX Overage, AVP IX Overage LP, AVP IX LLC, ARCH X Overage, AVP X Overage LP, AVP X LLC, Robert Nelsen, Keith Crandell, Kristina Burow, Steve Gillis and Clint Bybee.