{"filing":{"accession_number":"0001193125-26-374788","cik":"0001701108","ticker":"SPRO","company_name":"Spero Therapeutics, Inc.","form":"8-K","filing_date":"2026-08-28","report_date":"2026-08-28","primary_document":"d145223d8k.htm","primary_document_url":"https://www.sec.gov/Archives/edgar/data/1701108/000119312526374788/d145223d8k.htm"},"events":[{"id":30425,"run_id":27884,"accession_number":"0001193125-26-374788","anchor_item_number":"1.01","event_type":"dilutive_issuance","event_domain":"financial","is_material":true,"confidence":0.92,"summary":"Spero Therapeutics entered into an Open Market Sale Agreement with Jefferies to conduct an at-the-market (ATM) offering of up to $100 million in common stock under a universal shelf registration statement, representing a material dilutive equity issuance.","company_name":"Spero Therapeutics, Inc.","ticker":"SPRO","filing_date":"2026-08-28","form":"8-K","submitted_at":null,"items":[{"id":33006,"accession_number":"0001193125-26-374788","item_number":"1.01","item_title":null,"event_type":"dilutive_issuance","event_domain":"financial","is_material":true,"confidence":0.92,"reasoning":"Spero Therapeutics entered into an Open Market Sale Agreement with Jefferies to conduct an at-the-market (ATM) offering of up to $100 million in common stock. This is a dilutive equity issuance that would materially affect existing shareholders through potential dilution. The filing explicitly describes the offering as \"at-the-market offerings\" under Rule 415, and the company has filed a universal shelf registration statement to support the offering, which is a classic capital-raising mechanism for public companies.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-08-28T21:28:05.059972+00:00","company_name":"","ticker":null,"filing_date":""}]},{"id":30426,"run_id":27884,"accession_number":"0001193125-26-374788","anchor_item_number":"8.01","event_type":"financial_other","event_domain":"financial","is_material":false,"confidence":0.75,"summary":"Spero Therapeutics terminated its Controlled Equity Offering Sales Agreement with Cantor Fitzgerald effective August 28, 2026; no shares were sold under the agreement and no termination penalties were incurred.","company_name":"Spero Therapeutics, Inc.","ticker":"SPRO","filing_date":"2026-08-28","form":"8-K","submitted_at":null,"items":[{"id":33007,"accession_number":"0001193125-26-374788","item_number":"8.01","item_title":null,"event_type":"financial_other","event_domain":"financial","is_material":false,"confidence":0.75,"reasoning":"The disclosure reports termination of a Controlled Equity Offering Sales Agreement with Cantor Fitzgerald effective August 28, 2026. While the agreement was originally for up to $75 million in potential equity offerings, the Company states it had sold no shares under the agreement during 2024–2025 and incurred no termination penalties. The termination of an unused ATM facility is a routine administrative action that does not materially affect the registrant's financial position or investor assessment, as no capital was raised and no penalties were incurred.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-08-28T21:28:05.059972+00:00","company_name":"","ticker":null,"filing_date":""}]}],"classifications":[{"id":33006,"accession_number":"0001193125-26-374788","item_number":"1.01","item_title":null,"event_type":"dilutive_issuance","event_domain":"financial","is_material":true,"confidence":0.92,"reasoning":"Spero Therapeutics entered into an Open Market Sale Agreement with Jefferies to conduct an at-the-market (ATM) offering of up to $100 million in common stock. This is a dilutive equity issuance that would materially affect existing shareholders through potential dilution. The filing explicitly describes the offering as \"at-the-market offerings\" under Rule 415, and the company has filed a universal shelf registration statement to support the offering, which is a classic capital-raising mechanism for public companies.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-08-28T21:28:05.059972+00:00","company_name":"Spero Therapeutics, Inc.","ticker":"SPRO","filing_date":"2026-08-28"},{"id":33007,"accession_number":"0001193125-26-374788","item_number":"8.01","item_title":null,"event_type":"financial_other","event_domain":"financial","is_material":false,"confidence":0.75,"reasoning":"The disclosure reports termination of a Controlled Equity Offering Sales Agreement with Cantor Fitzgerald effective August 28, 2026. While the agreement was originally for up to $75 million in potential equity offerings, the Company states it had sold no shares under the agreement during 2024–2025 and incurred no termination penalties. The termination of an unused ATM facility is a routine administrative action that does not materially affect the registrant's financial position or investor assessment, as no capital was raised and no penalties were incurred.","classifier_version":"claude-haiku-4-5-20251001+prompt-a85dd512","taxonomy_version":"v1.3","classified_at":"2026-08-28T21:28:05.059972+00:00","company_name":"Spero Therapeutics, Inc.","ticker":"SPRO","filing_date":"2026-08-28"}]}