Research


October 17, 2024by Cristian0

Our latest preprint is out! Check it out on ArXiV.

Imagine making important decisions—like adjusting credit limits or recommending treatments—where there are multiple options instead of only “yes or no”. In our latest research, we asked whether traditional methods of estimating causal effects are enough for these complex situations. But what exactly is a causal effect? Simply put, a causal effect measures how one action directly impacts an outcome—like how increasing a credit limit might influence a customer’s spending behavior. Typically, these causal estimates help us make the “best” decision, but we found they don’t always tell the whole story.

Our study dives into what’s called a “multitreatment scenario”, where the range of possible actions isn’t limited to just one choice. For example, adjusting a credit limit could involve not only deciding whether to change it, but also determining by how much. In our case, the outcome we aimed to optimize was continuous—for instance the expected profit from adjusting credit card limits, and also the outcome was observable both before and after treatment.

We explored a new method that combines causal effect estimation with additional criteria like uncertainty measures and a “prediction condition”.  To truly enhance decision quality, we went beyond the traditional methods and added a fresh perspective. We brought in a measure called Conditional Value at Risk (CVaR), which allowed us to understand potential worst-case scenarios, not just the average outcome. Think of CVaR as a safety net that ensures we don’t overlook possible downsides while aiming for the best result.

We also introduced a “predictive condition” to help ensure our recommendations would actually be beneficial. Essentially, the predictive condition means we only recommend an action if we can confidently predict that the outcome will improve compared to where it started. In the context of adjusting credit limits, this meant that any suggested change had to show a clear increase in expected profit compared to the one corresponded to the original limit. This safeguard adds another layer of confidence, making sure that each decision made was a true upgrade rather than just a guess.

When applied to financial decision-making—adjusting credit card limits for consumers—we found that this combined approach outperformed traditional models. It wasn’t just about predicting the treatment effect, but also understanding how confident we could be about that effect while balancing it against other possible outcomes.

What makes this important is its broader applicability. Whether it’s deciding a financial policy, optimizing healthcare treatment doses, or managing resources, this refined approach could change how we navigate complex decisions. By blending causal analysis with a richer understanding of uncertainty, we can make recommendations that are not just statistically sound, but also practically more effective and personalized.

Our study is a step towards smarter decision-making in areas where “one size fits all” just doesn’t cut it. This work helps ensure that recommendations, whether in finance, healthcare, or any other field, are optimized not just for an average effect but for the best possible outcome across a range of real-world scenarios.

You can also listen to a machine-generated podcast of the preprint below.


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March 6, 2024by Cristian0

The Association for the Advancement of Artificial Intelligence (AAAI) conference is recognized as an elite conference in the field of artificial intelligence (AI), gathering a community of academic and industry experts engaged in both theoretical and applied AI research. The 38th AAAI conference was held in the city of Vancouver, Canada, from February 20th to 27th. It offered an excellent opportunity for sharing research work in AI, bridging potential collaborations, and offering the guidance of the direction of AI innovation.

Both Cristian and Jet attended. Jet presented our latest research: “Breaking Barriers: Unveiling Gender Disparities in Corporate Board Career Paths using Deep Learning.” This research was showcased in two workshops: the AI in Finance for Social Impact, organized by J.P. Morgan, and the AI for Financial Services, highlighting the cross-disciplinary impact and relevance of our work. In the former, the lab was also represented in the work “Extreme climate events and credit risk: stress testing approach for loans to SMEs based on network analysis”, presented by the PhD candidate Camilla Carpinelli, part of the group led by Prof. María Óskarsdóttir, at Reykjavík University.

Celebrating Recognition: Best Poster Award

Our collective efforts were recognized with the Best Poster Award at the workshop, a moment of great pride and joy for our team. We extend our deepest gratitude for this honour to the organizers, reaffirming our commitment to contributing meaningful insights and solutions in the realm of AI and social impact in banking.

Networking, Collaboration, and Future Horizons

The AAAI conference provided an excellent opportunity for engagement with the community of AI in Finance. Our team had a great time to meet, network, and exchanging ideas with fellow researchers and practitioners from both academia and industry. Notable interactions included enlightening discussions with peers from prestigious institutions and companies such as CMU, J.P. Morgan, and Capital One, among others.

As we reflect on our experiences at the AAAI conference, we are filled with gratitude for the opportunity to contribute to and partake in the global dialogue on AI. We look forward to attending the next one in 2025!


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February 6, 2024by Cristian0

 

Our latest paper is live! In this work, we study how to model financial contagion over dynamic networks. When people apply for loans, banks have a pretty important decision to make—can the borrower pay it back? Traditionally, banks use credit scores to assess risk, but our new research extends our previous research by delving deeper into the relationships borrowers have with others to better understand their chances of default.

Why Networks Matter in Credit Risk

Imagine you’re considering lending money to someone, but that person is part of a group where others have also borrowed money. This idea is at the heart of our study. Rather than seeing borrowers as isolated, we treat them as part of a bigger network. Their connections to other borrowers—like being in the same neighbourhood or using the same mortgage provider—might influence their financial behaviour.

Predicting Loan Defaults Using Dynamic Networks

Borrowers can be connected in various ways and these relationships evolve over time, making them dynamic. To better capture these connections, we developed a model that combines two powerful tools: Graph Neural Networks (GNNs) and Recurrent Neural Networks (RNNs). The GNNs help us map out these borrower networks, while the RNNs allow us to track how these relationships change over time. But that’s not all—we added an attention mechanism that prioritizes certain time points over others, based on their relevance to the borrower’s default risk.

What Did We Find?

We tested our model using real-world data from Freddie Mac, a major U.S. mortgage financier. The results were exciting—our model did a better job of predicting which borrowers were likely to default compared to traditional methods. It wasn’t just more accurate; it also provided a more profound understanding of why certain borrowers might struggle to repay loans.

Why This Matters

For banks and lenders, this research could change how they think about credit risk. By considering the connections between borrowers, lenders can make more informed decisions. This could even lead to more people getting approved for loans, especially those who might not have had a chance based on traditional credit scores alone. For borrowers, this kind of model could mean more opportunities. If banks can better understand the factors affecting risk, they might be more willing to take a chance on people who were previously overlooked.

What’s Next?

Our research shows that networks play a significant role in financial decisions, and there’s much more to explore. We’re excited to keep building on this work to better understand financial risk. The more we learn, the more we can help lenders and borrowers alike make informed financial decisions.

The paper is available, open to all and with CC-BY license, here. The code to replicate the paper can be found here.

Also, Juan Cristóbal Constain from Quipu created a podcast using NotebookLM from this post and the paper. Give it a listen below if you prefer!


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February 4, 2024by Cristian0

A bit late to the party, but as the first paper on this topic was recently published at EJOR (ArXiV, Journal), I thought it may merit the post.

Last year at the credit scoring conference, I was interviewed by Brendan Le Grange, host of the podcast How to Lend Money to Strangers. We discussed the paper I presented there, part of Sherly’s PhD thesis, on causal models for credit limit settings. The preprint of that paper will appear soon, read the first one meanwhile!

If you want to hear more about my thoughts on credit limit setting and how it relates to causal modelling, listen to the podcast episode in this link.



December 1, 2023by Daniel Abib0

We had a great time attending the 2023 INFORMS Annual Meeting that took place between October 15th to October 18th in Phoenix, AZ. This is one of the largest conferences in the field of OR, with 6,000+ attendees and 1,400+ sessions.

The BAL had a strong presence at the conference with four presentations:

  • On October 15th, we had two presentations:
    • Cristián Bravo presented the work with Kamesh Korangi and Christophe Mues on “Large-Scale Portfolio Optimization using Graph Attention Networks”.

 

  • Daniel Abib presented the work with Cristián Bravo, Raffaella Calabrese, and María Óskarsdóttir on “Optimal Feature Split in Classification Models with Dependency”.

 

  • On October 17th, Sahab Zandi presented the work with Kamesh Korangi, María Óskarsdóttir, Christophe Mues, and Cristián Bravo on “Leveraging Dynamic Multilayer Networks for Modelling Credit Risk Contagion in SMEs”.

 

  • On October 18th, Yuhao (Jet) Zhou presented the work with Collins Ntim, María Óskarsdóttir, Matthew Davison, and Cristián Bravo on “Uncovering the Network Power Gap: A Deep Learning Approach to Investigating Gender Disparities in the Boardrooms of Canadian Public Firms”.

 

We also had fun trying a few good restaurants in Scottsdale, AZ!

This was a great chance to showcase the preprints that will come out in the next few months. Stay tuned for them!



October 6, 2023by Cristian0

We had a great time attending the Credit Scoring and Credit Control Conference XVIII that took place between August 30th to September 1st in Edinburgh, UK. This conference bridges the academic/practitioner divide and is the world’s premier conference for credit scoring and credit risk related topics.

The BAL had a strong presence at the conference with six presentations:

  • On August 30th, Cristián presented the work with our PhD student Mahsa Tavakoli, cosupervised by Rohitash Chandra from UNSW, on “Multi-Modal Deep Learning for Midcap Credit Rating Prediction Using Text and Numerical Data”.
  • On August 31st we had two presentations:
    • Our collaborator Prof. María Óskarsdóttir from Reykjavík University, Iceland, presented the work by our PhD students Sahab Zandi and Kamesh Korangi, cosupervised by Prof. Christophe Mues from Southampton University and Cristián, titled “Credit Scoring with Dynamic Multilayer Graph Neural Networks”.
    • Cristián presented the work led by our PhD student Sherly Alfonso Sánchez, cosupervised by Prof. Kristina Sendova here at Western, called “Causal Learning for Credit Limit Adjustment in Revolving Lending Under Adversarial Goals”.
  • On September 1st, we had three:
    • Daniel Abib, who joined earlier this year as a postdoc at the Lab, presented the work coauthored with Prof. Raffaella Calabrese for Edinburgh University, Prof. María Óskarsdóttir, and Cristián. The work was called “Optimal Feature Split in Credit Risk Models with Dependency”.
    • Our PhD student Kamesh Korangi presented the work from his PhD, coauthored with Christophe Mues and Cristián, on “Deep Temporal Graph Networks for Behavioural Scoring Prediction in Revolving Credit Lines”.
    • Our PhD student Sahab Zandi presented the work with coautored with Kamesh, and cosupervised by Prof. María Óskarsdóttir, Prof. Christophe Mues, and Cristián. These last two works are part of the collaboration with one of the largest consumer banks in the world. Sahab’s presentation is titled “Modelling Credit Risk Contagion for SMEs over Supply Chains using Dynamic Multilayer Networks”.

The conference provided a great opportunity to meet and network with people in the field of credit risk from both academia and industry. We were honestly surprised and happy with the reception that we had from the conference attendants. We had many interesting talks and we look forward to what will come out of these chats!

We also had a blast having a reunion with some friends and colleagues after a while in Edinburgh!

We would like to thank the organizers, Professor Galina Andreeva and Professor Jonathan Crook from the Credit Research Centre at the University of Edinburgh, plus of course our collaborator Prof. Christophe Mues for hosting this wonderful conference. We look forward to attending the next one in 2025!

 



August 15, 2023by Cristian0

I had a great time presenting a keynote and a paper at the SIGKDD 2023, one of the elite conference in computer science. In my personal opinion, the KDD is the top applied data science conference, as NeurIPS is a bit too theoretical, while the KDD is a bit more integrative. Lots of papers this year in network science and causal learning, which was encouraging when evaluating the current research lines of the group.

I presented two works in the Machine Learning in Finance workshop of the conference:

  • The keynote “Leveraging Deep Learning for Multimodal Data Analysis in Credit Risk Assessment“, where I summarized the latest work of the lab in using multimodal data for the analysis of credit risk in midcaps and retail lending. I presented results of our latest preprints (paper on midcapspaper on mortgages) and preliminary results on using LiDAR for mortgage analysis and social network analysis for credit risk modelling. I shared the stage again with three other keynotes from Bloomberg and Blackrock, the same groups that presented in the Columbia-Bloomberg seminar in May we also presented in, and with Srijan Kumar from Georgiatech. Srijan was keynote in the NeurIPS workshop we presented our paper on influencer detection (NeurIPS paper, journal preprint). The machine learning in finance world seems to be pretty small!
  • The paper “Graph Attention Networks for Portfolio Optimisation: Empirical Evidence for Mid-Caps” by our PhD student Kamesh Korangi. Kamesh couldn’t attend as the US visas are taking forever. In this talk I showed the preliminary results of our work on using GATs for optimizing portfolios. We are really excited about this work! I can’t wait to show the world about in the near future. Stand by for the preprint, it should be available in a few months. The presentation itself will be available in a few weeks, I’ll update this post when it is.

It was a fantastic experience to attend the KDD in person. Sadly, we weren’t able to do so in 2020 due to the pandemic, where we presented the preliminary results of our paper in default propagation across multilayer networks (KDD paper, YouTube video with the presentation at CORS 2021, extended journal paper). It was great to be able to present now and share with so many top researchers.

The conference was in Long Beach, so I also got to have some great weather.

Cristian in front of the sunny Long Beach Convention Center

The acceptance rate of the conference was higher than previous years, around 20%. However, the MLF workshop was even more selective with only around 10% of the papers being selected for spotlight talks! It was great to be in such an exclusive group.

Slide with the acceptance rate of the KDD conference per areas. Finance is 22%.

Also, it was great to see so many Latin Americans there! We had a few meetings and even some went salsa dancing. We were very pleased to also meet with Ricardo Baeza-Yates, a legend in the field.

Latin Americans sharing a lunch at the KDD.

Overall, it was a great experience. Hopefully we’ll be able to attend to KDD 2024 in Barcelona!



Our research focuses on using reinforcement learning (RL) to address the credit limit modification problem for companies offering credit card products. This involves two main challenges: defining the RL problem for this specific task and training the RL agent without conducting online experiments with customers.

To define the RL problem, we consider the financial history of credit card holders and the expected losses due to defaults when deciding whether to increase or maintain their credit limits. The actions available are increasing the limit or keeping it the same. We calculate the reward function based on the expected profit, considering the revolving aspect of credit card usage. This differs from previous studies that overlooked this aspect in profit calculations.

To train the RL agent offline, we use a two-stage model to simulate the balance after taking an action. This involves selecting the balance type and predicting the balance amount using a regressor model. Through our experiments, we found that our trained Double-Q learning agent outperformed other strategies, including the one used by Rappi, a Latin American fintech company known for its delivery and commerce services that has also ventured into banking with its RappiCard credit card, and that was our collaborator in this research.

Our research contributes by providing a conceptual framework for applying RL to credit limit adjustments and emphasizes data-driven decision-making rather than relying solely on expert judgments. Furthermore, we discovered that incorporating additional predictors did not improve the performance of our simulator. This implies that fintech companies do not necessarily have an advantage over traditional banking institutions in this specific task.  Figure 1  provides an overview of the proposed methodology’s general workflow.

 

 

 

 

 

 

 

 

 

 

 

Figure 1: Methodology’s general workflow.

Link to the working paper: https://arxiv.org/abs/2306.15585



June 28, 2023by Daniel Abib0

By Mahsa Tavakoli @Bal:

Our research study was undertaken with the aim of enhancing the accuracy of predicting company credit ratings, a critical factor in evaluating their financial stability. Unlike previous studies that solely focused on structured data, such as numbers and figures, we recognized the significance of incorporating other, non-structured information. Thus, our primary objective was to evaluate the effectiveness of employing advanced deep learning models to merge both structured and unstructured data, particularly textual information. Through this approach, we sought to provide a more comprehensive analysis and improve the overall predictive capabilities of the models. In our quest for the optimal approach, we conducted thorough testing of various fusion strategies and deep learning models, including CNN, LSTM, GRU, and BERT. To our surprise, we discovered that a CNN-based model (Figure 2), which effectively amalgamated data from diverse sources, outperformed more intricate models. Leveraging this model enabled us to achieve highly precise credit rating predictions.

Furthermore, we delved into the contribution of different data types to these predictions. Textual data, such as insights shared by company managers, played a pivotal role, particularly during challenging periods like the COVID-19 pandemic. This underscored the significance of contextual information and managerial perspectives in accurately predicting credit ratings.

Additionally, our research encompassed a comparative analysis of ratings provided by various agencies. Moody’s credit ratings emerged as the frontrunner, surpassing those of other agencies like Standard & Poor’s and Fitch Ratings, especially in medium-term predictions.

Collectively, our research provides a comprehensive framework that empowers rating agencies and financial institutions to make well-informed decisions when assigning credit ratings. By incorporating a combination of structured and unstructured data and leveraging the most effective deep learning models, they can significantly enhance the precision of credit rating predictions, thereby augmenting their overall decision-making process.

Fig1: Blending Textual Managers’ Insights and Companies Numerical Data for Precise Credit Rating Predictions

Fig2: Architecture of the CNN ensemble for the best model, showing
the convolution and dropout layers with two streams of data that includes
text and numerical data (N1, N2, N3, N4).

Link to the working paper: https://arxiv.org/abs/2304.10740



May 20, 2023by Cristian0

I had the true honour of being invited by Prof. Ali Hirsa to present at this excellent workshop. The organizers review 1400 abstracts published during the year and select the ones that according to them reflect the most significant research at the intersection of ML and Finance. Our work with Kamesh Korangi and Christophe Mues, “A transformer-based model for default prediction in mid-cap corporate markets” [paper, ArXiV], was one of them!

Excellent roster of speakers, including people from MIT, Stanford, Blackrock, Morgan Stanley, and of course, the hosts Columbia and Bloomberg. Everything went amazing except that the IT team lost a few of my slides, but I think the audience did not mind very much. I look forward to keep engaged with such an excellent team moving forward. Here are a few pictures of the event.

Cristián on the stage before his presentation at the Alfred Lerner Hall

The presentation was at the amazing Alfred Lerner hall at Columbia University. 400 attendants from industry and academia were present.

The stage at the Alfred Lerner hall