AI Cut Our Research Time From 7 Days to 15 Minutes — Gareth Yoder, Vanguard

Gareth Yoder leads the cash program at Vanguard. He walks through modernizing a cash ledger that takes up to 30 million calls a day, running data, producer and consumer migrations in parallel. The turning point was exposing the legacy code base to AI tools through an MCP server. Research that took a mainframe engineer seven days dropped to 15 minutes. He closes with five lessons: make legacy code AI-queryable, treat migration docs as product, reimagine instead of lift-and-shift, adopt AI incrementally, and never skip observability. Chapters: - 00:00 Intro - 01:10 What a cash ledger is - 01:52 Three migrations in parallel - 02:32 Legacy code over MCP: 7 days to 15 minutes - 03:20 Data migration - 04:12 Producer migration - 06:38 Consumer migration - 08:58 Onboarding 50 consumers - 11:11 What we learned - 13:12 Five takeaways Gareth Yoder, Vanguard: https://investor.vanguard.com Join us in SF for the second annual AIE CODE summit: https://aie.codes our last flagship summit of 2026. Applications live now!