HackingFinancial ServicesTechnologyFinanceCustomer Data InvolvedCredentialsIdentity (basic)Government IDMediumContained

Topstep Brokerage

bd_73c0da0a1e966032 · schema v1 · pii pii-v1

Severity

Medium

Discovered

—

Filed

Jan 12, 2026

To disclose

—

Affected

9state residents only

Linked

10 filings

Confidence

67%

Full breach record for Topstep Brokerage →

Topstep LLC notified Massachusetts residents of a cybersecurity incident involving high-volume traffic attacks blocked at the Web Application Firewall. The company forced password resets for affected accounts and is implementing mandatory multifactor authentication. Complimentary 24-month identity monitoring via Experian is being offered. No specific dates for discovery or occurrence were provided in the sample letter.

J jump to incidentP pin to compareR raw source

Incident timeline — partial

? — ?

Breach window unknown

Jan 12, 2026

Filed

—

Corroborated · see linked filings

Compliance clocks stay unassessable until a regulatory filing lands. Dashed segments fill in automatically when corroboration arrives.

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

Vermont State AGbd_feda97c361d069982026-01-16 · +4dVerified
New Hampshire State AGbd_1ba3a5d6f8186b382026-01-05 · +7dVerified
Indiana State AGbd_d103e7440b81fd372026-01-20 · +8dVerified
Indiana State AGbd_e1bd3f7d6444d49f2026-01-20 · +8dVerified

Show 5 more filings ↓up to 23d gap

Indiana State AGbd_865cfabcd1482f642025-12-30 · +13dVerified
Indiana State AGbd_0a892e5fb23ecfef2025-12-22 · +21dVerified
New Hampshire State AGbd_204febfe40a8a4232025-12-22 · +21dVerified
Maine State AGbd_ac7762ff013459da2025-12-22 · +21dCandidate
Indiana State AGbd_f926e2f8532bba862025-12-20 · +23dVerified

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

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

Discovered: —
Materiality determined: —
Notification sent: —
Affected individuals: 9state-resident count only
Data types: CredentialsIdentity (basic)Government ID
Attack vector: Unknown
MITRE ATT&CK: T1190 Exploit Public-Facing Application
Threat actor: External
Initial access: exploit_public_facing

During the incident: IP addresses identified as sending high volumes of traffic were immediately blocked at the Web Application Firewall (WAF) and ALB level
Forced a password reset for all potentially affected accounts, specifically prohibiting the re-use of old passwords
Offering complimentary access to Experian IdentityWorks for 24 months
Changes made: Working to implement additional security features to its login processes to assist data subjects protect their information, such as mandatory multifactor authentication
Source: Quoted from the filing itself, not independently verified.

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

Massachusetts State AG+23d · this page

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://www.mass.gov/doc/2026-39-topstep-llc/download
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Jan 12, 2026
Raw hash: fd84e659c91904e9b98c93bfb418c58d201f3a68a37dcabb89223f1ef4613d3b

Linked disclosures

Regulatory filings (9) · sorted by filing gap

Reporting entityTopstep Brokerage

Victim entityTopstep Brokerage

IncidentUnknown

Stated responseIP addresses identified as sending high volumes of traffic were immediately blocked at the Web Application Firewall (WAF) and ALB level

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancewww.mass.gov