HackingTechnologyInformationStolen CredentialsCustomer Data InvolvedDelayed DiscoveryIdentity (basic)Government IDMediumContained

Topstep Brokerage

bd_1ba3a5d6f8186b38 · schema v1 · pii pii-v1

Severity

Medium

Discovered

Sep 8, 2025

Filed

Jan 5, 2026

To disclose

5 weeks

Affected

1state residents only

Linked

10 filings

Confidence

66%

Full breach record for Topstep Brokerage →

Topstep LLC notified the New Hampshire Attorney General of a security incident involving password stuffing. Between September 8 and October 16, 2025, unauthorized access occurred, potentially exposing names and Social Security numbers of one New Hampshire resident. Topstep discovered the breach on December 3, 2025, engaged cybersecurity experts, and began notifying affected individuals on December 30, 2025, offering credit monitoring services.

J jump to incidentP pin to compareR raw source

Incident timeline

discovery → filing · 17 weeks / 119 days

Sep 8, 2025

Begins

Sep 8, 2025

Discovered

Jan 5, 2026

Filed

vs. sector median

14 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_865cfabcd1482f642025-12-30 · +6dVerified
Massachusetts State AGbd_73c0da0a1e9660322026-01-12 · +7dVerified
Vermont State AGbd_feda97c361d069982026-01-16 · +11dVerified
Indiana State AGbd_0a892e5fb23ecfef2025-12-22 · +14dVerified

Show 5 more filings ↓up to 16d gap

New Hampshire State AGbd_204febfe40a8a4232025-12-22 · +14dVerified
Maine State AGbd_ac7762ff013459da2025-12-22 · +14dCandidate
Indiana State AGbd_d103e7440b81fd372026-01-20 · +15dVerified
Indiana State AGbd_e1bd3f7d6444d49f2026-01-20 · +15dVerified
Indiana State AGbd_f926e2f8532bba862025-12-20 · +16dVerified

Name: MCDONALD HOPKINS LLC
norm: mcdonald hopkins

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

Discovered: Sep 8, 2025
Breach occurred: Sep 8, 2025 – Oct 16, 2025
Undetected for: 0 daysoccurrence → discovery
Materiality determined: —
Notification sent: Dec 30, 2025
Affected individuals: 1state-resident count only
Data types: Identity (basic)Government ID
Attack vector: Unauthorized Access
MITRE ATT&CK: T1110 Brute ForceT1119 Automated Collection
Threat actor: External
Regulator citations: Notified New Hampshire Office of the Attorney General
Initial access: valid_credentials

During the incident: Engaged leading cybersecurity experts to identify what personal information, if any, was involved
Conducted a thorough investigation
Offered affected residents complimentary credit monitoring service
Notified affected residents starting on December 30, 2025
Changes made: Provided best practices to protect their information
Advised affected residents to remain vigilant in reviewing financial account statements
Advised affected residents about the process for placing a fraud alert and/or security freeze on their credit files
Provided contact information for the consumer reporting agencies and the Federal Trade Commission
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 5 weeks(33 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

New Hampshire State AG+2d

Maine State AG+2d

Indiana State AG+10d

New Hampshire State AG+16d · this page

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-20260105.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Jan 5, 2026
Raw hash: 7042d9abae81a0137ed80ae67277411749578b0cbd6012c7cd4d40794aeead85

Linked disclosures

Regulatory filings (9) · sorted by filing gap

Reporting entityMCDONALD HOPKINS LLC

Victim entityTopstep Brokerage

Incidentdiscovered Sep 8, 2025

Stated responseEngaged leading cybersecurity experts to identify what personal information, if any, was involved

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancemm.nh.gov