Comparable stake leader
FMR LLC
SEC ownership of Boundless Bio, Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001782303.
Disclosed value leader
TANG CAPITAL MANAGEMENT LLC
Comparable rows
4/50
Latest evidence
16 Oct 2026
- Public ticker
- BOLD on Nasdaq
- Parsed ownership sources
-
13F, 13D/G, and 3/4/5
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
FMR LLC
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
4 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
FMR LLC
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
16 Oct 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0001782303
- Issuer location
- La Jolla, CA
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of Boundless Bio, Inc. (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
TANG CAPITAL MANAGEMENT LLC
Comparable rows
4/50
Latest evidence
16 Oct 2026
13F
13D/G
3/4/5
Lead comparable stake: 12%
46 rows are not safely comparable across share classes.
13D/G row: FMR LLC
Showing 1-8 of 50 holder rows.
Quick read
FMR LLC leads the comparable SEC ownership view at 12%.
4 of 50 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 4
FMR LLC
12%
TANG CAPITAL MANAGEMENT LLC
11%
Zachary Hornby
9.8%
ADAR1 Capital Management, LLC
8.8%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| FMR LLC |
13F
13D/G
Company
|
12%
Reported 13D/G
· 31 Dec 2025
|
$6,452,638
2,581,055 shares
|
— | 30 Jun 2026 |
| TANG CAPITAL MANAGEMENT LLC |
3/4/5
13D/G
13F
10%+ Owner · Company
|
11%
Reported 13D/G
· 23 Jun 2026
|
$13,724,912
5,688,627 shares
|
+$1,810,336 | 16 Oct 2026 |
| Zachary Hornby |
13D/G
3/4/5
President & CEO, Director
|
9.8%
Reported 13D/G
· 14 Oct 2025
|
$6,237,022
2,426,857 shares
|
$0 | 14 Oct 2025 |
| ADAR1 Capital Management, LLC |
13D/G
13F
Company
|
8.8%
Reported 13D/G
· 30 Jun 2026
|
$4,920,540
1,968,216 shares
|
$0 | 30 Jun 2026 |
| Kevin Tang |
3/4/5
10%+ Owner
|
—
denominator unverified
|
$13,724,912
5,688,627 shares
|
+$1,810,336 | 16 Oct 2026 |
| Wellington Biomedical Innovation Master Investors (Cayman) I L.P. |
3/4/5
10%+ Owner
|
—
denominator unverified
|
—
556,233 shares
|
— | 02 Apr 2024 |
| RA CAPITAL MANAGEMENT, L.P. |
3/4/5
10%+ Owner
|
—
denominator unverified
|
—
295,844 shares
|
— | 02 Apr 2024 |
| Kristina Burow |
3/4/5
10%+ Owner
|
—
denominator unverified
|
—
16,000 shares
|
-$39,840 | 01 Jul 2026 |
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.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to buying over the last 12 months. Net value: +$3,102,752.
Buys
$3,729,374
Insiders: 2
Sells
$626,622
Insiders: 15
Net
+$3,102,752
Shares: +1,277,194
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 1,521,794
Shares: 244,600
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 298,948 | 36,600 | $699,186 | $108,702 | +$590,484 |
| 3-6 | 1,222,846 | 208,000 | $3,030,188 | $517,920 | +$2,512,268 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 30 reporting-owner rows connected to Boundless Bio, Inc.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
30
Largest Forms 3/4/5 holder
TANG CAPITAL MANAGEMENT LLC
Net 12M change
+$3,102,752
Latest report
16 Oct 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | $13,724,912 | +$1,810,336 | +15% | Filing P/S | 16 Oct 2026 |
| Kevin Tang | 10%+ Owner | $13,724,912 | +$1,810,336 | +15% | Filing P/S | 16 Oct 2026 |
| ARCH Venture Partners X Overage, L.P. | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| Clinton Bybee | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| Kristina Burow | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| ARCH Venture Partners IX Overage, L.P. | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| ARCH Venture Partners IX, LLC | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| ARCH Venture Partners X, LLC | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| Steven Gillis | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| ARCH Venture Partners IX, L.P. | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| Robert Nelsen | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| ARCH Venture Fund IX, L.P. | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| Keith Crandell | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| ARCH Venture Fund IX Overage, L.P. | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| ARCH Venture Fund X Overage, L.P. | 10%+ Owner | $0 | -$39,840 | -100% | Mixed | 01 Jul 2026 |
| Robert Doebele | Chief Medical Officer | Mixed | 23 Jan 2026 | |||
| David A. Hinkle | Senior VP, Finance, Controller and Treasurer | Mixed | 23 Jan 2026 | |||
| Jessica Oien | Chief Legal Officer and Corporate Secretary | Mixed | 23 Jan 2026 | |||
| Nancy Whiting | Director | Mixed | 15 Jun 2026 | |||
| Klaus W. Wagner | Chief Medical Officer | Mixed | 19 Aug 2024 |
Recent insider transactions for Boundless Bio, Inc.
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Tang Kevin | BOLD | Common Stock | Purchase | 0.01% | $521 | $2.37 | 220 | 2,990,109 | 20 Oct 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.01% | $521 | $2.37 | 220 | 2,990,109 | 20 Oct 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 1.05% | $72,519 | $2.33 | 31,069 | 2,989,889 | 19 Oct 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 1.05% | $72,519 | $2.33 | 31,069 | 2,989,889 | 19 Oct 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 4.16% | $276,553 | $2.34 | 118,185 | 2,958,820 | 16 Oct 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 4.16% | $276,553 | $2.34 | 118,185 | 2,958,820 | 16 Oct 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Sale | -0.64% | $54,351 | $2.97 | -18,300 | 2,840,635 | 26 Aug 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Sale | -0.64% | $54,351 | $2.97 | -18,300 | 2,840,635 | 26 Aug 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 0.1% | $7,259 | $2.44 | 2,975 | 2,858,935 | 21 Jul 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.1% | $7,259 | $2.44 | 2,975 | 2,858,935 | 21 Jul 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 0.06% | $3,960 | $2.44 | 1,623 | 2,855,960 | 20 Jul 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.06% | $3,960 | $2.44 | 1,623 | 2,855,960 | 20 Jul 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 0.01% | $647 | $2.44 | 265 | 2,854,337 | 17 Jul 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.01% | $647 | $2.44 | 265 | 2,854,337 | 17 Jul 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 0.65% | $45,118 | $2.44 | 18,491 | 2,854,072 | 16 Jul 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.65% | $45,118 | $2.44 | 18,491 | 2,854,072 | 16 Jul 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 0.06% | $3,904 | $2.44 | 1,600 | 2,835,581 | 15 Jul 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.06% | $3,904 | $2.44 | 1,600 | 2,835,581 | 15 Jul 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 1.57% | $106,624 | $2.43 | 43,878 | 2,833,981 | 14 Jul 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 1.57% | $106,624 | $2.43 | 43,878 | 2,833,981 | 14 Jul 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 1.76% | $116,671 | $2.42 | 48,211 | 2,790,103 | 13 Jul 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 1.76% | $116,671 | $2.42 | 48,211 | 2,790,103 | 13 Jul 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | 1.61% | $105,382 | $2.43 | 43,367 | 2,741,892 | 10 Jul 2026 | See Footnote |
| Kevin Tang | BOLD | Common Stock | Purchase | 1.61% | $105,382 | $2.43 | 43,367 | 2,741,892 | 10 Jul 2026 | See Footnote |
| Tang Kevin | BOLD | Common Stock | Purchase | $17.36 | $2.48 | 7 | 2,698,525 | 09 Jul 2026 | See Footnote | |
| Kevin Tang | BOLD | Common Stock | Purchase | $17.36 | $2.48 | 7 | 2,698,525 | 09 Jul 2026 | See Footnote | |
| Tang Kevin | BOLD | Common Stock | Purchase | 0.53% | $35,271 | $2.46 | 14,338 | 2,698,518 | 08 Jul 2026 | By LP |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.53% | $35,271 | $2.46 | 14,338 | 2,698,518 | 08 Jul 2026 | By LP |
| Tang Kevin | BOLD | Common Stock | Purchase | 0.59% | $39,209 | $2.48 | 15,810 | 2,684,180 | 07 Jul 2026 | By LP |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.59% | $39,209 | $2.48 | 15,810 | 2,684,180 | 07 Jul 2026 | By LP |
| Tang Kevin | BOLD | Common Stock | Purchase | 1.02% | $67,384 | $2.49 | 27,062 | 2,668,370 | 06 Jul 2026 | By LP |
| Kevin Tang | BOLD | Common Stock | Purchase | 1.02% | $67,384 | $2.49 | 27,062 | 2,668,370 | 06 Jul 2026 | By LP |
| Tang Kevin | BOLD | Common Stock | Purchase | 0.37% | $24,454 | $2.49 | 9,821 | 2,641,308 | 02 Jul 2026 | By LP |
| Kevin Tang | BOLD | Common Stock | Purchase | 0.37% | $24,454 | $2.49 | 9,821 | 2,641,308 | 02 Jul 2026 | By LP |
| Keith Crandell | BOLD | Common Stock | Sale | -100% | $39,840 | $2.49 | -16,000 | 0 | 01 Jul 2026 | See footnote |
| Keith Crandell | BOLD | Common Stock | Sale | -100% | $39,840 | $2.49 | -16,000 | 0 | 01 Jul 2026 | See footnote |
| Keith Crandell | BOLD | Common Stock | Sale | -100% | $39,840 | $2.49 | -16,000 | 0 | 01 Jul 2026 | See footnote |
| Keith Crandell | BOLD | Common Stock | Sale | -100% | $39,840 | $2.49 | -16,000 | 0 | 01 Jul 2026 | See footnote |
| Keith Crandell | BOLD | Common Stock | Sale | -100% | $39,840 | $2.49 | -16,000 | 0 | 01 Jul 2026 | See footnote |
| Keith Crandell | BOLD | Common Stock | Options Exercise | 16,000 | 16,000 | 01 Jul 2026 | See footnote | |||
| Keith Crandell | BOLD | Common Stock | Options Exercise | 16,000 | 16,000 | 01 Jul 2026 | See footnote | |||
| Keith Crandell | BOLD | Common Stock | Options Exercise | 16,000 | 16,000 | 01 Jul 2026 | See footnote | |||
| Keith Crandell | BOLD | Common Stock | Options Exercise | 16,000 | 16,000 | 01 Jul 2026 | See footnote | |||
| Keith Crandell | BOLD | Common Stock | Options Exercise | 16,000 | 16,000 | 01 Jul 2026 | See footnote | |||
| Keith Crandell | BOLD | Stock Option (right to buy) | Options Exercise | -100% | -16,000 | 0 | 01 Jul 2026 | See footnote | ||
| Keith Crandell | BOLD | Stock Option (right to buy) | Options Exercise | -100% | -16,000 | 0 | 01 Jul 2026 | See footnote | ||
| Keith Crandell | BOLD | Stock Option (right to buy) | Options Exercise | -100% | -16,000 | 0 | 01 Jul 2026 | See footnote | ||
| Keith Crandell | BOLD | Stock Option (right to buy) | Options Exercise | -100% | -16,000 | 0 | 01 Jul 2026 | See footnote | ||
| Keith Crandell | BOLD | Stock Option (right to buy) | Options Exercise | -100% | -16,000 | 0 | 01 Jul 2026 | See footnote | ||
| ARCH Venture Fund IX, L.P. | BOLD | Common Stock | Sale | -100% | $39,840 | $2.49 | -16,000 | 0 | 01 Jul 2026 | See footnote |
* marks a reported price that did not pass the local price check.