A Bank Trained Its Own Foundation Model to Catch Fraud — Freddy Lecue, Wells Fargo

Freddy Lecue explains how Wells Fargo pre-trained its own transformer from scratch on billions of customer transactions instead of words. The model learns to predict the next transaction, and that one backbone can then be fine-tuned for fraud detection, credit line decisions, anti-money laundering and marketing. He covers the hardest part, turning tabular data like amounts, timing, merchants and zip codes into tokens, plus the model's size and training setup. On fraud, it caught more fraudulent transactions with fewer false alarms than the production XGBoost model, while staying fast enough fo