{"schema_version":"secwatch.filing_event.v1","accession":"0001193125-26-079286","form_type":"8-K","ticker":"MBX","cik":"0001776111","company_name":"MBX Biosciences, Inc.","filed_at":"2026-02-27T23:59:59+00:00","discovered_at":"2026-05-14T18:02:36.139296+00:00","generated_at":"2026-05-15T23:08:37.782707+00:00","sec_items":["1.01","9.01","5.02"],"event_type":"leadership","sentiment":"negative","materiality_score":0.65,"calibrated_materiality_score":0.65,"confidence":"high","headline":"MBX Biosciences CFO Richard Bartram resigns; John Smither named interim CFO","bullets":["CFO Richard Bartram resigns effective March 15, 2026; will serve as consultant post-resignation.","John Smither appointed Interim CFO effective March 16, 2026; base salary $325k, target bonus 40%, $25k sign-on.","Lease entered for 13,642 sqft office/lab in Burlington, MA; aggregate base rent ~$3.4M over 4-year term.","Departure not due to dispute; search for permanent CFO underway."],"urls":{"canonical":"https://secwatch.observer/filing/0001193125-26-079286","json":"https://secwatch.observer/filing/0001193125-26-079286.json","markdown":"https://secwatch.observer/filing/0001193125-26-079286.md","text":"https://secwatch.observer/filing/0001193125-26-079286.txt","edgar_index":"https://www.sec.gov/Archives/edgar/data/1776111/000119312526079286/0001193125-26-079286-index.htm","edgar_primary_document":"https://www.sec.gov/Archives/edgar/data/1776111/000119312526079286/mbx-20260224.htm"},"model":{"generated_by":"deepseek-v4-flash:cloud@v2","generated_at":"2026-05-15T23:08:37.782707+00:00"},"review":{"review_status":"machine_generated","human_reviewed":false,"corrected":false,"correction_note":null,"correction_timestamp":null,"superseded_by":null,"related_filings":[]},"source_grounded_claims":[{"claim_id":"d49435ef9ac35d5b42b2801a54dd3dc4444ba3e9","claim":"MBX Biosciences, Inc. entered into Lease Agreement with 5 Burlington Woods, LLC valued at approximately $3.4 million (effective 2026-02-24).","evidence_excerpt":"On February 24, 2026, MBX Biosciences, Inc. (the “Company”) entered into a lease agreement (the “Lease Agreement”) with 5 Burlington Woods, LLC (\"5 Burlington Woods\") to lease approximately 13,642 square feet of new office and laboratory space in Burlington, MA","evidence_source":"SEC 8-K Item 1.01/1.02","evidence_url":"https://www.sec.gov/Archives/edgar/data/1776111/000119312526079286/0001193125-26-079286-index.htm","confidence":0.9,"family_label":"Material Agreements","details":[{"label":"Action","value":"entry"},{"label":"Agreement","value":"lease"},{"label":"Counterparty","value":"5 Burlington Woods, LLC"},{"label":"Value","value":"approximately $3.4 million"},{"label":"Effective","value":"2026-02-24"}],"fact_type":"material_agreement"}],"license":"Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer"}