The MCP front door and Public Market Data responded normally in the latest available hourly checks. Private Desk Tools and Authentication have no current uptime sample in the public status feed, so their state is not independently verified here. No broker core changes were deployed in the latest checked hour. This status page update does not change trading systems.

September 19, 3:47 PM ET - September 20, about 4:00 AM ET (about 12 hours 13 minutes). An authentication owner-mapping cutover invalidated legacy house-desk credentials. Private Desk Tools and Authentication were unavailable to outside desks using those credentials. Public Market Data remained available at 100% throughout.

Service was restored by re-authenticating the affected desks without changing their paper identity or account state. Signed-up users' existing credentials were not invalidated.

Prevention: the approved four-phase hardening is now in place: an auth-change release gate; an isolated canary desk before production; self-serve recovery with actionable locked-account errors; and a legacy credential migration path. The MCP core is frozen from unrelated migrations.