Mercer Advisors data breach: 143,104 people after a January 2026 intrusion into client-data systems

How many people were affected by the Mercer Advisors data breach?

143,104 in total, according to the number Mercer Advisors reported to Indiana. The letter gives no count.

Regulator	Who it counts	Number	Recorded
Indiana attorney general	Total reported by Mercer Advisors	143,104	Notice March 31, 2026
Texas attorney general	Texans	15,486	Posted April 2, 2026
Massachusetts consumer affairs office	Massachusetts residents	2,178	Reported March 31, 2026
Indiana attorney general	Indiana residents	703	Notice March 31, 2026

Texas's attorney general lists 15,486 Texans for Mercer Advisors, posted on April 2, 2026.

Massachusetts' record marks Social Security numbers as breached, along with financial accounts and driver's licenses. That differs from the sample letter's statement on Social Security numbers, so check the list in your own letter.

Was my Social Security number taken in the Mercer Advisors breach?

The sample letter says no. Massachusetts' record marks Social Security numbers as breached, and Texas's record lists Social Security number information among the types involved, so letters may differ from person to person. The letter does say that not every item applied to every person.

What happened at Mercer Advisors?

Date	Event
January 22, 2026	Unauthorized access to client-data systems (on or around)
March 25, 2026	Mercer Advisors determines that personal information was obtained
March 31, 2026	Letters dated; notices to Indiana and Massachusetts

The firm says it worked with outside cybersecurity experts, contained the incident, blocked the access, added safeguards and reported the issue to law enforcement. Letters went out 68 days after the access and six days after the firm confirmed what was taken.

What is Mercer Advisors offering?

Item	Detail from the letter
Service	Experian IdentityWorks Credit Plus for two years: credit monitoring, dark web monitoring and identity protection
Help line	833-918-0255, Monday through Friday, 8 a.m. to 8 p.m. Central Time, except U.S. holidays

The guide to credit monitoring offers compares offers like this one.

What Washington's attorney general recorded

Washington's attorney general lists a report from Mercer Advisors Inc., received on March 31, 2026, with 7,470 Washington residents affected and a breach date of January 22, 2026. For those residents the record lists names, Social Security numbers, driver's license or state ID numbers, financial and banking information, dates of birth, passport numbers, usernames and passwords or security answers and email address and password/security question answers as compromised.

What the documents leave open

• How the unauthorized party got into the client-data systems.
• Why the Massachusetts and Texas records list Social Security numbers when the sample letter rules them out.
• Which kinds of accounts the account numbers belong to.