Independent public-records tracker. Not a government website.Facts from official state, HHS and SEC filings

Largest data breaches of 2013

The 1 data breaches first reported in 2013 with the most people affected, using official totals from the filings. Where no official total was filed, the number is the sum of state filings and is labelled "At least". Facts come from official filings with US state attorneys general, the U.S. Department of Health and Human Services (HHS) and the SEC; each breach page links its sources.

Updated Oct 21, 2026 · Showing 1–1 of 1

# Organization First filed People affected Information exposed Filed with
1 Advocate Health and Hospitals Corporation, d/b/a Advocate Medical GroupAdvocate Health and Hospitals Corporation breach history 4,029,530Official total
  • Medical information
HHS, California AG

Other years

People affected is the official total from a filing, or “At least” the sum of state filings where no total was filed. Spotted an error? Report a correction.