{"filing":{"accession_number":"0001193125-26-278570","cik":"0001782303","ticker":"BOLD","company_name":"Boundless Bio, Inc.","form":"8-K","filing_date":"2026-06-23","report_date":null,"primary_document":"d159021d8k.htm","primary_document_url":"https://www.sec.gov/Archives/edgar/data/1782303/000119312526278570/d159021d8k.htm"},"events":[{"id":13022,"run_id":11556,"accession_number":"0001193125-26-278570","anchor_item_number":"1.01","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.98,"summary":"Boundless Bio entered into a definitive merger agreement with Serapha Bio, whereby Serapha will be the surviving entity and Boundless stockholders will own approximately 3.7% of the combined company post-closing. The transaction includes a concurrent $230 million private placement financing and is expected to close in Q4 2026.","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23","form":"8-K","submitted_at":null,"items":[{"id":10044,"accession_number":"0001193125-26-278570","item_number":"1.01","item_title":"Entry into a Material Definitive Agreement.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.99,"reasoning":"This Item 1.01 discloses entry into a definitive merger agreement between Boundless Bio and Serapha Bio, with Serapha surviving as a wholly owned subsidiary of Boundless Bio. The filing details the exchange ratio, ownership structure post-closing (Serapha shareholders ~96.3%, Boundless shareholders ~3.7%), concurrent $230 million private placement financing, and closing conditions. This is a material acquisition/change of control transaction that would substantially affect investor assessment of the registrant.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"","ticker":null,"filing_date":""},{"id":10047,"accession_number":"0001193125-26-278570","item_number":"5.01","item_title":"Changes in Control of Registrant.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.98,"reasoning":"Item 5.01 incorporates Item 1.01 by reference, and the press release (EX-99.1) announces a definitive merger agreement between Boundless Bio and Serapha Bio, with Serapha as the surviving entity. The transaction includes a $230 million concurrent private placement and represents a change of control where pre-merger Boundless stockholders will own only ~3.7% of the combined company. This is a material acquisition/merger transaction requiring disclosure under Item 1.01.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"","ticker":null,"filing_date":""},{"id":10049,"accession_number":"0001193125-26-278570","item_number":"7.01","item_title":"Regulation FD Disclosure.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.98,"reasoning":"The disclosure announces entry into a definitive merger agreement between Boundless Bio and Serapha Bio, with Serapha combining into Boundless in an all-stock merger. The combined company will operate as Serapha Bio and trade on Nasdaq. This is a material acquisition/change of control transaction, supported by a concurrent $230 million private placement. The press release and pre-recorded call explicitly detail the merger terms, ownership structure (3.7% Boundless / 96.3% Serapha post-closing), expected closing in Q4 2026, and strategic rationale.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"","ticker":null,"filing_date":""},{"id":10050,"accession_number":"0001193125-26-278570","item_number":"8.01","item_title":"Other Events.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.95,"reasoning":"The Item 8.01 disclosure centers on Boundless Bio's decision to discontinue clinical development of BBI-940 due to lower-than-expected human oral bioavailability. However, the supplemental exhibits reveal the material event is a definitive merger agreement between Boundless Bio and Serapha Bio, with a concurrent $230 million private placement. The merger represents a change of control and material acquisition activity, with Boundless stockholders expected to own only 3.7% of the combined company post-closing. This is the dominant material event disclosed in this filing.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"","ticker":null,"filing_date":""}]},{"id":13023,"run_id":11556,"accession_number":"0001193125-26-278570","anchor_item_number":"3.02","event_type":"dilutive_issuance","event_domain":"financial","is_material":true,"confidence":0.95,"summary":"Serapha Bio is raising $230 million through a private placement of capital stock in connection with the proposed merger, with approximately $138 million already funded in a Series A financing and $92 million expected to close concurrently with the merger closing.","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23","form":"8-K","submitted_at":null,"items":[{"id":10046,"accession_number":"0001193125-26-278570","item_number":"3.02","item_title":"Unregistered Sales of Equity Securities.","event_type":"dilutive_issuance","event_domain":"financial","is_material":true,"confidence":0.95,"reasoning":"Item 3.02 discloses a $230 million private placement of Serapha capital stock in connection with the proposed merger, with approximately $138 million already funded in a Series A financing and $92 million expected to close concurrently with the merger. The shares are being issued in private placements exempt from registration under Section 4(a)(2) of the Securities Act and Regulation D. This is a classic dilutive equity issuance that materially affects the ownership structure and capitalization of the combined company.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"","ticker":null,"filing_date":""}]},{"id":13024,"run_id":11556,"accession_number":"0001193125-26-278570","anchor_item_number":"2.05","event_type":"workforce_reduction","event_domain":"operational","is_material":true,"confidence":0.95,"summary":"In connection with the merger agreement, Boundless Bio announced a workforce reduction of approximately 75% of its workforce, with estimated one-time costs of $3.0–$5.0 million primarily for termination benefits and severance, substantially completed in Q3 2026.","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23","form":"8-K","submitted_at":null,"items":[{"id":10045,"accession_number":"0001193125-26-278570","item_number":"2.05","item_title":"Costs Associated with Exit or Disposal Activities.","event_type":"workforce_reduction","event_domain":"operational","is_material":true,"confidence":0.95,"reasoning":"The Item 2.05 disclosure explicitly announces a workforce reduction of approximately 75% of Boundless Bio's workforce in connection with the merger agreement, with estimated one-time costs of $3.0–$5.0 million primarily for termination benefits and severance. The reduction is expected to be substantially completed in Q3 2026 with charges recognized in Q3 financial results. This is a classic workforce reduction event under Item 2.05, material to investors assessing the company's operational restructuring and financial impact.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"","ticker":null,"filing_date":""}]},{"id":13025,"run_id":11556,"accession_number":"0001193125-26-278570","anchor_item_number":"5.02","event_type":"exec_appointment","event_domain":"governance","is_material":true,"confidence":0.85,"summary":"In connection with the merger transaction, Oien was appointed as President and principal executive officer of Boundless Bio, replacing departing CEO Hornby, along with compensatory arrangements including transaction bonuses and acceleration of stock options.","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23","form":"8-K","submitted_at":null,"items":[{"id":10048,"accession_number":"0001193125-26-278570","item_number":"5.02","item_title":"Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.75,"reasoning":"The Item 5.02 section discloses multiple executive transitions (Hornby's departure as CEO, Oien's appointment as President and principal executive officer, and departures of Drs. Doebele and Hassig), along with compensatory arrangements (separation agreements with severance, consulting agreements, and amended offer letters with transaction bonuses and acceleration of stock options). While the Item nominally covers executive changes and compensation, the filing's core substance—referenced in the opening phrase \"In connection with the Contemplated Transaction\"—is the merger agreement between Boundless Bio and Serapha Bio announced in the press release (EX-99.1). The executive transitions and compensation arrangements are all triggered by and subordinate to the merger transaction itself. The merger is the material event; the executive changes are consequences of it.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"","ticker":null,"filing_date":""}]}],"classifications":[{"id":10044,"accession_number":"0001193125-26-278570","item_number":"1.01","item_title":"Entry into a Material Definitive Agreement.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.99,"reasoning":"This Item 1.01 discloses entry into a definitive merger agreement between Boundless Bio and Serapha Bio, with Serapha surviving as a wholly owned subsidiary of Boundless Bio. The filing details the exchange ratio, ownership structure post-closing (Serapha shareholders ~96.3%, Boundless shareholders ~3.7%), concurrent $230 million private placement financing, and closing conditions. This is a material acquisition/change of control transaction that would substantially affect investor assessment of the registrant.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23"},{"id":10045,"accession_number":"0001193125-26-278570","item_number":"2.05","item_title":"Costs Associated with Exit or Disposal Activities.","event_type":"workforce_reduction","event_domain":"operational","is_material":true,"confidence":0.95,"reasoning":"The Item 2.05 disclosure explicitly announces a workforce reduction of approximately 75% of Boundless Bio's workforce in connection with the merger agreement, with estimated one-time costs of $3.0–$5.0 million primarily for termination benefits and severance. The reduction is expected to be substantially completed in Q3 2026 with charges recognized in Q3 financial results. This is a classic workforce reduction event under Item 2.05, material to investors assessing the company's operational restructuring and financial impact.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23"},{"id":10046,"accession_number":"0001193125-26-278570","item_number":"3.02","item_title":"Unregistered Sales of Equity Securities.","event_type":"dilutive_issuance","event_domain":"financial","is_material":true,"confidence":0.95,"reasoning":"Item 3.02 discloses a $230 million private placement of Serapha capital stock in connection with the proposed merger, with approximately $138 million already funded in a Series A financing and $92 million expected to close concurrently with the merger. The shares are being issued in private placements exempt from registration under Section 4(a)(2) of the Securities Act and Regulation D. This is a classic dilutive equity issuance that materially affects the ownership structure and capitalization of the combined company.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23"},{"id":10047,"accession_number":"0001193125-26-278570","item_number":"5.01","item_title":"Changes in Control of Registrant.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.98,"reasoning":"Item 5.01 incorporates Item 1.01 by reference, and the press release (EX-99.1) announces a definitive merger agreement between Boundless Bio and Serapha Bio, with Serapha as the surviving entity. The transaction includes a $230 million concurrent private placement and represents a change of control where pre-merger Boundless stockholders will own only ~3.7% of the combined company. This is a material acquisition/merger transaction requiring disclosure under Item 1.01.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23"},{"id":10048,"accession_number":"0001193125-26-278570","item_number":"5.02","item_title":"Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.75,"reasoning":"The Item 5.02 section discloses multiple executive transitions (Hornby's departure as CEO, Oien's appointment as President and principal executive officer, and departures of Drs. Doebele and Hassig), along with compensatory arrangements (separation agreements with severance, consulting agreements, and amended offer letters with transaction bonuses and acceleration of stock options). While the Item nominally covers executive changes and compensation, the filing's core substance—referenced in the opening phrase \"In connection with the Contemplated Transaction\"—is the merger agreement between Boundless Bio and Serapha Bio announced in the press release (EX-99.1). The executive transitions and compensation arrangements are all triggered by and subordinate to the merger transaction itself. The merger is the material event; the executive changes are consequences of it.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23"},{"id":10049,"accession_number":"0001193125-26-278570","item_number":"7.01","item_title":"Regulation FD Disclosure.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.98,"reasoning":"The disclosure announces entry into a definitive merger agreement between Boundless Bio and Serapha Bio, with Serapha combining into Boundless in an all-stock merger. The combined company will operate as Serapha Bio and trade on Nasdaq. This is a material acquisition/change of control transaction, supported by a concurrent $230 million private placement. The press release and pre-recorded call explicitly detail the merger terms, ownership structure (3.7% Boundless / 96.3% Serapha post-closing), expected closing in Q4 2026, and strategic rationale.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23"},{"id":10050,"accession_number":"0001193125-26-278570","item_number":"8.01","item_title":"Other Events.","event_type":"ma_activity","event_domain":"operational","is_material":true,"confidence":0.95,"reasoning":"The Item 8.01 disclosure centers on Boundless Bio's decision to discontinue clinical development of BBI-940 due to lower-than-expected human oral bioavailability. However, the supplemental exhibits reveal the material event is a definitive merger agreement between Boundless Bio and Serapha Bio, with a concurrent $230 million private placement. The merger represents a change of control and material acquisition activity, with Boundless stockholders expected to own only 3.7% of the combined company post-closing. This is the dominant material event disclosed in this filing.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-06-23T12:31:56.235519+00:00","company_name":"Boundless Bio, Inc.","ticker":"BOLD","filing_date":"2026-06-23"}]}