Insider trading · Q3 2026 · CIK 1782303

Boundless Bio, Inc. (BOLD) insider trading.

Name: Boundless Bio, Inc. insider transactions, Q3 2026
Creator: U.S. Securities and Exchange Commission

In Q3 2026, insiders at Boundless Bio, Inc. reported 21 non-derivative transactions on 8 Forms 3, 4 and 5: 16 open-market purchases worth $800K and 3 sales worth $134K.

Transactions: 21
Purchases (P): 16
Sales (S): 3
Net shares, P minus S: 274,790
Insiders: 4
Last filed: 2026-08-28

Insiders

Insider	Relationship	Transactions	Buys	Sales
Tang Kevin / Tang Capital Management LLC	TenPercentOwner	16	16	0
ARCH Venture Partners IX, L.P. / ARCH Venture Fund IX, L.P. / ARCH Venture Partners IX, LLC / ARCH Venture Partners IX Overage, L.P. / ARCH Venture Fund X Overage, L.P. / ARCH Venture Fund IX Overage, L.P. / ARCH Venture Partners X Overage, L.P. / ARCH Venture Partners X, LLC	TenPercentOwner	2	0	1
GILLIS STEVEN / CRANDELL KEITH / NELSEN ROBERT / Burow Kristina / BYBEE CLINTON	TenPercentOwner	2	0	1
Tang Capital Management LLC / Tang Kevin	TenPercentOwner	1	0	1

Transactions

21 non-derivative rows, newest transaction first. Shares and prices as filed.
Date	Insider	Code	Shares	Price	Owned after	Filing
2026-08-26	Tang Capital Management LLC / Tang Kevin	S (D)	18,300	$2.97	2,840,635	Form 4
2026-07-21	Tang Kevin / Tang Capital Management LLC	P (A)	2,975	$2.44	2,858,935	Form 4
2026-07-20	Tang Kevin / Tang Capital Management LLC	P (A)	1,623	$2.44	2,855,960	Form 4
2026-07-17	Tang Kevin / Tang Capital Management LLC	P (A)	265	$2.44	2,854,337	Form 4
2026-07-16	Tang Kevin / Tang Capital Management LLC	P (A)	18,491	$2.44	2,854,072	Form 4
2026-07-15	Tang Kevin / Tang Capital Management LLC	P (A)	1,600	$2.44	2,835,581	Form 4
2026-07-14	Tang Kevin / Tang Capital Management LLC	P (A)	43,878	$2.43	2,833,981	Form 4
2026-07-13	Tang Kevin / Tang Capital Management LLC	P (A)	48,211	$2.42	2,790,103	Form 4
2026-07-10	Tang Kevin / Tang Capital Management LLC	P (A)	43,367	$2.43	2,741,892	Form 4
2026-07-09	Tang Kevin / Tang Capital Management LLC	P (A)	7	$2.48	2,698,525	Form 4
2026-07-08	Tang Kevin / Tang Capital Management LLC	P (A)	14,338	$2.46	2,698,518	Form 4
2026-07-07	Tang Kevin / Tang Capital Management LLC	P (A)	15,810	$2.48	2,684,180	Form 4
2026-07-06	Tang Kevin / Tang Capital Management LLC	P (A)	27,062	$2.49	2,668,370	Form 4
2026-07-02	Tang Kevin / Tang Capital Management LLC	P (A)	9,821	$2.49	2,641,308	Form 4
2026-07-01	ARCH Venture Partners IX, L.P. / ARCH Venture Fund IX, L.P. / ARCH Venture Partners IX, LLC / ARCH Venture Partners IX Overage, L.P. / ARCH Venture Fund X Overage, L.P. / ARCH Venture Fund IX Overage, L.P. / ARCH Venture Partners X Overage, L.P. / ARCH Venture Partners X, LLC	M (A)	16,000	$1.03	16,000	Form 4
2026-07-01	ARCH Venture Partners IX, L.P. / ARCH Venture Fund IX, L.P. / ARCH Venture Partners IX, LLC / ARCH Venture Partners IX Overage, L.P. / ARCH Venture Fund X Overage, L.P. / ARCH Venture Fund IX Overage, L.P. / ARCH Venture Partners X Overage, L.P. / ARCH Venture Partners X, LLC	S (D)	16,000	$2.49	0	Form 4
2026-07-01	GILLIS STEVEN / CRANDELL KEITH / NELSEN ROBERT / Burow Kristina / BYBEE CLINTON	M (A)	16,000	$1.03	16,000	Form 4
2026-07-01	GILLIS STEVEN / CRANDELL KEITH / NELSEN ROBERT / Burow Kristina / BYBEE CLINTON	S (D)	16,000	$2.49	0	Form 4
2026-07-01	Tang Kevin / Tang Capital Management LLC	P (A)	71,612	$2.49	2,631,487	Form 4
2026-06-30	Tang Kevin / Tang Capital Management LLC	P (A)	25,930	$2.54	2,559,775	Form 4
2026-06-30	Tang Kevin / Tang Capital Management LLC	P (A)	100	$2.5	2,559,875	Form 4

Transaction codes in this quarter

P: 16 S: 3 M: 2

Get BOLD insider transactions through the API

Request with your API key

curl "https://sec-api.dev/api/v1/insider-transactions?period=2026q3&cik=1782303&limit=100" \
  -H "Authorization: Bearer $SEC_API_KEY"

Insider trading API guide · BOLD company page · Boundless Bio, Inc. on SEC.gov

Questions

Are insiders buying or selling Boundless Bio, Inc. (BOLD)?

In Q3 2026, insiders at Boundless Bio, Inc. reported 21 non-derivative transactions on 8 Forms 3, 4 and 5: 16 open-market purchases worth $800K and 3 sales worth $134K. Grants, tax withholding and option exercises are counted as transactions but are not purchases or sales.

Where do these Boundless Bio, Inc. insider trades come from?

From the SEC Insider Transactions Data Sets for Q3 2026, which republish the Forms 3, 4 and 5 filed on EDGAR. Each row links to its filing on SEC.gov.

Source: SEC Insider Transactions Data Sets, Q3 2026, retrieved 2026-10-27. Footnotes, derivative holdings and amendments are in the linked filings. Not investment advice.

Plain-text version for agents and LLMs: /insider-trading/bold.md

Independent. Not affiliated with, endorsed by, or sponsored by the U.S. Securities and Exchange Commission. Data is reproduced from public SEC filings and datasets. Not investment advice.