Security key
10170A100
Boundless Bio, Inc. - Common Stock, par value $0.0001 per share (BOLD)
CUSIP: 10170A100
Q1 2026 13F Holders as of 31 Mar 2026
- Security type / class
- Equity / Common Stock, par value $0.0001 per share
- Total 13F shares
- 8,485,823
- Total 13F value
- $9,333,021
- Share change
- -295,115
- SEC-reported price per share
- $1.10
- Number of holders
- 36
- Value change
- -$347,924
- Number of buys
- 10
- Number of sells
- 15
- Shares outstanding
- 24,763,847
Holder snapshot
6 signals
Security identity
Names, identifiers, and filing context for this profile.
1 source field
Report period
Q1 2026
Institutions
36
Top holders
10
BOLD full security history
Ownership snapshot
Full 13F holder table
Newer quarter: Q2 2026
Previous quarter: Q4 2025
Boundless Bio, Inc. SEC filings
Boundless Bio, Inc. company facts
Broader feeds
Reporting periods
Holder history for CUSIP 10170A100
Recent filing periods:
Ownership snapshot
Top reported holders of BOLD - Boundless Bio, Inc. - Common Stock, par value $0.0001 per share (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
FMR LLC
Disclosed value leader
Zachary Hornby
Comparable rows
15/15
Latest evidence
31 Dec 2025
13F
13D/G
3/4/5
Lead comparable stake: 12%
13D/G row: FMR LLC
Showing 1-6 of 15 holder rows.
Quick read
FMR LLC leads the comparable SEC ownership view at 12%.
15 of 15 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens FMR LLC's linked filing trail.
Comparable ownership
Top 5
FMR LLC
12%
Zachary Hornby
9.8%
CITADEL ADVISORS LLC
5.5%
Stonepine Capital Management, LLC
2.9%
SECTORAL ASSET MANAGEMENT INC
2.7%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-6 of 15 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| FMR LLC |
13F
13D/G
Company
|
12%
from 13D/G
|
$3,220,826
2,684,022 shares
|
— | 31 Dec 2025 |
| Zachary Hornby |
13D/G
3/4/5
President & CEO, Director
|
9.8%
|
$6,237,022
2,426,857 shares
|
$0 | 14 Oct 2025 |
| CITADEL ADVISORS LLC |
13F
Company
|
5.5%
|
$1,624,685
1,353,904 shares
|
— | 31 Dec 2025 |
| Stonepine Capital Management, LLC |
13F
Company
|
2.9%
|
$852,085
710,071 shares
|
— | 31 Dec 2025 |
| SECTORAL ASSET MANAGEMENT INC |
13F
Company
|
2.7%
|
$814,289
678,574 shares
|
— | 31 Dec 2025 |
| VANGUARD GROUP INC |
13F
Company
|
2.7%
|
$795,308
662,757 shares
|
— | 31 Dec 2025 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
13F holder rows
Institutional holders as of Q1 2026
Investor-level positions for this CUSIP, loaded as an interactive table.
Institutions
36
Shares
8,485,823
Rows available
36
| Investor | Option | Weight % | Change % | SEC-reported value | * Price | Shares | Share Change | Activity | Report Period |
|---|
* SEC-reported price is the security price as of the portfolio date and can indicate the last known price at which the security was still held. The marker flags a reported price that did not pass the local price check.
Compare Q1 2026 vs Q4 2025 Across Filers
Q4 2025 holders
35
Q1 2026 holders
36
Holder diff
1
| Investor | Q4 2025 Shares | Q1 2026 Shares | Share Diff | Share Chg % | Q4 2025 value | Q1 2026 value | Value change | Value Chg % |
|---|
Trend: ostatnie 8 kwartałów (+ wybrane okresy porównania).
Quarterly Holders Trend
Quarterly Value Trend
Quarterly Shares Trend