HackingFinancial ServicesTechnologyFinanceStolen CredentialsBrute ForceCustomer Data InvolvedIdentity (basic)Government IDFinancialHighContained

Topstep Brokerage

bd_204febfe40a8a423 · schema v1 · pii pii-v1

Severity

High

Discovered

Nov 26, 2025

Filed

Dec 22, 2025

To disclose

26 days

Affected · nationwide

1,9222 in this filing

Linked

10 filings

Confidence

64%

Full breach record for Topstep Brokerage →

Topstep LLC experienced a credential-stuffing attack on November 26, 2025, resulting in unauthorized access to user accounts. Approximately 1,922 individuals were affected, including 2 New Hampshire residents. Compromised data included names, contact info, dates of birth, and tax/SSN information. Topstep contained the incident, forced password resets, and is implementing mandatory MFA.

J jump to incidentP pin to compareR raw source

Incident timeline

discovery → filing · 26 days

Nov 26, 2025

Begins

Nov 26, 2025

Discovered

Dec 22, 2025

Filed

vs. sector median

5 wks faster

This filing is one of 10 about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (9) · sorted by filing gap

Indiana State AGbd_0a892e5fb23ecfef2025-12-22Verified
Maine State AGbd_ac7762ff013459da2025-12-22Candidate
Indiana State AGbd_f926e2f8532bba862025-12-20 · +2dVerified
Indiana State AGbd_865cfabcd1482f642025-12-30 · +8dVerified

Show 5 more filings ↓up to 29d gap

New Hampshire State AGbd_1ba3a5d6f8186b382026-01-05 · +14dVerified
Massachusetts State AGbd_73c0da0a1e9660322026-01-12 · +21dVerified
Vermont State AGbd_feda97c361d069982026-01-16 · +25dVerified
Indiana State AGbd_d103e7440b81fd372026-01-20 · +29dVerified
Indiana State AGbd_e1bd3f7d6444d49f2026-01-20 · +29dVerified

Name: Topstep Brokerage
norm: topstep brokerage
Domain: topstepbrokerage.com

Name: Topstep Brokerage
norm: topstep brokerage
Domain: topstepbrokerage.com
Industry: Financial ServicesllmTechnologyllm

Discovered: Nov 26, 2025
Breach occurred: Nov 26, 2025
Undetected for: 0 daysoccurrence → discovery
Materiality determined: —
Notification sent: Dec 22, 2025
Affected individuals: 1,922state + nationwide
Data types: Identity (basic)Government IDFinancial
Data elements: Social Security numberDate of birth
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid AccountsT1110.003 Credential Stuffing
Threat actor: External
Regulator citations: Notified New Hampshire Office of Consumer Protection
Initial access: valid_credentials

During the incident: Blocked the cyber threat actors’ IP addresses
Forced a password reset for all potentially affected accounts
Prohibited the re-use of old passwords
Conducted a thorough investigation and analysis of the attack
Provided credit monitoring services provided by Experian
Changes made: Continues to review its IT systems and security infrastructure
Working to implement additional security features to its login processes
Implementing mandatory multifactor authentication
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 26 days(26 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 10 filings · 5 states

View merged incident ↗

Indiana State AGDec 20 · first

Indiana State AG+2d

Maine State AG+2d

New Hampshire State AG+2d · this page

Indiana State AG+10d

New Hampshire State AG+16d

Massachusetts State AG+23d

Vermont State AG+27d

Indiana State AG+31d

Pattern: first filing Dec 20 (IN), last Jan 20 (IN) — a 31-day rolling notification. Rolling spreads often mean counsel is filing as thresholds trip per state. Why this link?

Evidence ladder

Leak-site claim

Attacker assertion only. Establishes: claim date, group, alleged victim.

Press / market report

Unlocks: incident narrative, operational impact. Still no compliance clock.

State AG / regulator filingThis record

Unlocks: discovery date, data types, affected count, compliance clock.

SEC 8-K / victim statement

Unlocks: materiality, stated response, full audit trail. Ceiling removed.

Source URL: https://mm.nh.gov/files/uploads/doj/remote-docs/topstep-20251222.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Dec 22, 2025
Raw hash: be150cf038b91c2e207faaa7b30544e1d4ab961b44162a83c5ddf34dab07e16e

Linked disclosures

Regulatory filings (9) · sorted by filing gap

Reporting entityTopstep Brokerage

Victim entityTopstep Brokerage

Incidentdiscovered Nov 26, 2025

Stated responseBlocked the cyber threat actors’ IP addresses

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancemm.nh.gov