Fintech AI Lab

Fintech · AI · Notes

Notes from fintech
and AI.

Things I run into working in fintech, and notes from studying AI on the side.

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  • Financial AI
  • Payments
  • LLM Systems
  • AI Coding
  • World Models

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  1. 01 Financial AI [FDS] Finding the 0.015%: Transaction Sequence Models, Anomaly Detection and Graphs In 2024, card fraud in Europe was 0.015% of transactions by count, and fraud labels can take a week or more to arrive. How WeChat Pay, Stripe and Visa have added transaction sequence foundation models alongside their existing models, why XGBoost is still there, label-free anomaly detection and the foundation models from Leman Akoglu's group at CMU, and graph methods for finding fraud rings. 2026.10.22 2 links
  2. 02 Financial AI Where Transformers Fit in Credit Models: Affirm, Revolut, Parafin and Ant Affirm has put a transformer in front of its underwriting model. It reads each credit-report account as one token and feeds the resulting embeddings into XGBoost. From Revolut's PRAGMA and Parafin's ParaFormer to Ant's Falcon TST and BYB, where financial companies have placed transformers next to tree models, and how to read the numbers they publish. 2026.10.21 4 links
  3. 03 Payments Will AI Companies Become Payments Companies? Who Makes Money When an Agent Buys Meta plans to keep its personal agent Muse free and take a small fee from the transactions it completes. Where AI companies, payment firms and clouds are each coming at payments from, the four kinds of money on one agent purchase and the liability attached to each, and whose side a fee-earning agent is on, seen from fintech. 2026.10.01 3 links
  4. 04 Financial AI Sales Forecasting (2) Inside Time Attention and Group Attention A time series transformer lays a seller's sales and covariates out as a grid, then alternates attention across time and down the series in a group. Following the Chronos-2 architecture in PyTorch from tokenisation to the group mask, and what to watch when using it on sales, including why daily quantiles don't add up to a monthly one. 2026.09.29 3 links
  5. 05 Financial AI Sales Forecasting (1) From Tree Models to Chronos For a fintech that lends against sales, forecasting sits at the centre of limits, repayment and risk. First decide whether to predict the amount, the growth rate or the distribution, because that choice carries all the way into model selection. From LightGBM quantile regression to the Chronos family of time series transformers. 2026.09.29 4 links
  6. 06 LLM Systems Nobody Touched a Line of Code and the System Broke: The Paths by Which Data Quietly Rots The types check out, the values sit in range, and only the model goes strange. A price column that started recording dollars instead of won, a RAG system answering confidently from a two-year-old research report, and a feedback loop where the model's own misreading hardens into ground truth. 2026.08.15 4 links

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Financial AI 6 posts

Financial AI & fraud

  • Agentic Engineering in …
  • [FDS] How Does Stripe J…
  • Sales Forecasting (1) F…
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Payments 6 posts

Payments & commerce

  • The Age of AI Paying
  • WeChat's Different Road
  • How Chinese Fintech Act…
On the map
LLM Systems 6 posts

LLMs & agents

  • Better Agents Come From…
  • The Model Is Smart, So …
  • How Do You Grade an LLM…
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AI Coding 4 posts

AI coding

  • Productivity in AI Codi…
  • [Notes] These Days My M…
  • Taking Apart Andrew Ng'…
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World Models 6 posts

World models

  • Norms Are Not in the Da…
  • World Models (1) What C…
  • World Models (2) Why No…
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