Substack won't share official numbers, but it seems like a pretty significant data breach.

The hacker claims to have stolen nearly 700,000 Substack user records, including email addresses and phone numbers.

Substack said that customer data was accessed in October 2025, but wasn't discovered until early February.

Michael Burry of "The Big Short" fame just debuted a Substack blog that promises a "front row seat" to his famous predictions and analyses.

Michigan Gov. Gretchen Whitmer (D) started a Substack on Monday as speculation swirls about a potential 2028 presidential bid ...