Architect for an order-of-magnitude increase in accounts, positions, and daily transaction volume: capacity modeling, tenant-aware partitioning and sharding strategy, per-domain read replicas, continuous aggregates and materialized views, connection pooling, and load testing ahead of demand. Lead multi-region resilience for data stores: convert production clusters to Aurora Global Database, instrument replication lag against tiered RTO and RPO commitments, and own documented failover, failback, and recurring recovery drills.