Where Mobile Money Goes Now
Apps beat games in mobile revenue for the first time in 2025. GenAI led the charge with $3.5B in growth. Eight charts show who controls the app economy.
3 min readQuantitative Finance, AI & Technology
Blog about Personal Projects, Articles and Papers on Economics, Finance and Technology
The Variance Tax
Variance drain is the hidden cost of volatility: why a portfolio averaging +10% can lose money. The ½σ² formula explains the gap between paper and real returns.
4 min read Finance
Claude Opus 4.6: Anthropic's New Flagship AI Model for Agentic Coding
Claude Opus 4.6 brings a 1M token context window, 68.8% ARC-AGI-2, and Agent Teams to Claude Code. Full benchmark comparison vs GPT-5.2 and Gemini 3 Pro with pricing analysis.
6 min read AI
Buying the Haystack Might Not Work This Year
a16z sees AI fundamentals thriving with 80% GPU utilization. AQR sees the CAPE at the 96th percentile. Both have data. Both may be right.
4 min read Finance
Bandits and Agents: Netflix and Spotify Recommender Stacks in 2026
How hybrid recommender systems balance multi-armed bandits against LLM inference cost economics in 2026. A deep dive into Netflix recommendation algorithm architecture and Spotify's AI DJ recommender system.
5 min read AI
Is Private Equity Just Beta With a Lockup?
AQR's 2026 data shows private equity returning 4.2% versus 3.9% for public equities. The 30bp illiquidity premium barely justifies years of lockup.
3 min read Finance
Britain's Strategic Limbo
Britain faces strategic isolation: locked out of EU defense cooperation, unwilling to join Trump's coalition. The mid-Atlantic bridge has nowhere to land.
2 min read Commentary
The Rise of Middle Power Realism
At Davos 2026, Carney told allies to take down the signs of the liberal order. Middle powers are learning to navigate between giants without illusions.
4 min read Commentary
The Most Expensive Assumption in AI
Sara Hooker's research challenges the trillion-dollar scaling thesis. Compact models now outperform massive ones as diminishing returns hit AI.
4 min read Finance
Enterprise AI Strategy is Backwards
85% of AI projects fail. Only 26% translate pilots to production. The winners automate the coordination layer where employees spend 57% of their workday.
2 min read AI
Big in Japan
Japan holds $5 trillion in foreign assets. With 30-year JGB yields now above 3%, the carry trade that defined Japanese investing faces new friction.
2 min read Commentary
Ozempic is Reshaping the Fast Food Industry
Cornell research: GLP-1 users cut grocery spending 5.3%, fast food 8%. With 16% household adoption and savory snacks down 10%, food stocks face headwinds.
4 min read Finance
Does AI mean the demand on labor goes up?
AI was supposed to free us. The Jevons paradox plays out in real time: efficiency expands workload, not leisure. 77% of workers say AI added to their work.
2 min read AI
Repo might be even bigger than we thought
New OFR data reveals $12.6 trillion in daily repo exposures—$700 billion larger than previous estimates. The plumbing of modern money remains poorly understood.
5 min read Commentary
The Market Can Stay Irrational Longer Than You Can Stay Solvent
Steve Eisman explains how U.S. equity markets have structurally decoupled from everyday economic reality through concentration and passive investing.
4 min read Finance
Beyond Vector Search: Why LLMs Need Episodic Memory
Context windows aren't memory. Explore EM-LLM's episodic architecture, knowledge graph tools like Mem0 and Letta, and why vectors fail for sequential data.
3 min read AI
Praise by Name, Criticize by Category: Warren Buffett Retires at 95
Buffett exits after paying $26.8B in taxes. What 60 years of letters reveal about admitting mistakes, insurance float, and why Abel inherits $300B in cash.
4 min read Finance
Bitcoin Security
Academic paper finds Bitcoin 51% attack costs $6.77B. Derivatives enable attack profits via shorting. Analysis of why attacks haven't happened yet.
4 min read Finance
Apple's AI Bet: Playing the Long Game or Missing the Moment?
Apple's $157B cash pile and Gemini-powered Siri shift show a restrained AI strategy. Analysis of whether Apple wins as AI models become commodities.
3 min read AI
Book Review: Why Machines Learn
Why Machines Learn explains ML math with real equations and geometric intuition. Review of Ananthaswamy's approach to neural networks, PCA, and GANs.
3 min read AI
How AI is Shaping My Investment Portfolio for 2026
Rebalancing for 2026: reducing S&P 500 at 40× CAPE, adding Europe after Germany's €1T pivot, and bonds at 4.2% yields. Full allocation rationale.
10 min read Finance
Not Logan Roy: Netflix vs. Paramount's Bidding War
Netflix's $72B Warner Bros deal vs Paramount's hostile $30/share tender. Deal mechanics, aggregation theory, and why internet distributors win streaming.
7 min read Finance
Nike's Crisis and the Economics of Brand Decay
Nike lost $27.5B in market value by weakening three complementary assets simultaneously. Analysis of how Donahoe's strategy destroyed competitive advantage.
7 min read Finance
Michael Burry's $379 Newsletter
Michael Burry launches Substack warning AI markets mirror 1999. His Nvidia-Cisco comparison, the GPU depreciation debate, and what hyperscalers need to justify capex.
5 min read Finance![Is AI Really Eating the World? AGI, Networks, Value [2/2]](https://static.philippdubach.com/ograph/ograph-eatingtheworld2.jpg)
Is AI Really Eating the World? AGI, Networks, Value [2/2]
AGI predictions miss the point. Multiple competing models means price war. Value flows to applications, customer relationships, and vertical integrators.
7 min read AI![Is AI Really Eating the World? [1/2]](https://static.philippdubach.com/ograph/ograph-eatingtheworld1.jpg)
Is AI Really Eating the World? [1/2]
Benedict Evans' AI analysis argues 'we don't know how it matters.' But current evidence points to model commoditization: $400B capex, 97% price drops.
5 min read AI
Weather Forecasts Have Improved a Lot
Four-day forecasts now match one-day accuracy from 30 years ago. How AI models like WeatherNext 2 use CRPS training to preserve extreme weather signals.
2 min read AI
GLP-1 Receptor Agonists in ASUD Treatment
Phase 2 trial shows semaglutide reduces alcohol craving and heavy drinking with effect sizes exceeding naltrexone. What this means for AUD treatment.
2 min read Medicine
Damodaran on Gold's 2025 Surge
Damodaran argues gold is a collectible, not an asset you can value. So why hold it? As insurance against hyperinflation and market dislocations in 2025.
1 min read Finance
The Bicycle Needs Riding to be Understood
Build an LLM agent in 50 lines of Python. Why context engineering and emergent behaviors are best understood through hands-on experimentation, not theory.
1 min read AI
AI Models as Standalone P&Ls
OpenAI lost $11.5B in one quarter. But Anthropic CEO Dario Amodei argues each AI model is independently profitable. Here's why the math is complicated.
4 min read AI
Working with Models
Diffusion models corrupt data into noise, then reverse the process. Learn the math with Stefano Ermon's Stanford CS236 course, free on YouTube.
1 min read AI![Pozsar's Bretton Woods III: Three Years Later [2/2]](https://static.philippdubach.com/ograph/ograph-Pozsar2.jpg)
Pozsar's Bretton Woods III: Three Years Later [2/2]
Part 2/2: Assessing Bretton Woods III three years later. Evidence shows gradual reserve diversification and gold strength, but also persistent dollar dominance.
6 min read Economics![Pozsar's Bretton Woods III: The Framework [1/2]](https://static.philippdubach.com/ograph/ograph-Pozsar1.jpg)
Pozsar's Bretton Woods III: The Framework [1/2]
Pozsar's Bretton Woods III: how Russia sanctions triggered a shift from Treasury-backed reserves to commodity-backed money. Part 1 of 2 on the framework.
7 min read Economics
Everything is a DCF Model
Michael Mauboussin's argument that every cash-generating asset is valued through a DCF model. Why this Morgan Stanley paper changed how I think about value.
1 min read Finance
The State of AI Report 2025
Critical analysis of the State of AI Report 2025 by Nathan Benaich: reasoning models, China's AI rise, business adoption growth, and survey bias concerns.
2 min read AI
Popular Science Nobel Prize
Mary Brunkow, Fred Ramsdell, and Shimon Sakaguchi won the 2025 Nobel Prize in Medicine for peripheral immune tolerance. Read the popular science summary.
1 min read Medicine
Agent-based Systems for Modeling Wealth Distribution
Agent-based modeling shows how random market transactions naturally produce extreme wealth concentration, and why even a small wealth tax changes everything.
2 min read Economics
Sentiment Trading Revisited
A Rutgers study finds news sentiment embeddings from OpenAI models cut stock price prediction errors by 40%. Time-independent models perform just as well.
2 min read FinanceNVIDIA Likes Small Language Models
NVIDIA's SLM research claims 40-70% of LLM tasks can shift to small language models. Here's what their cost analysis misses about real-world deployment.
3 min read AINovo Nordisk's Post-Patent Strategy
Amycretin's Phase 1 data shows 24.3% weight loss, beating Wegovy and Zepbound. How Novo Nordisk plans to replace its $20B Ozempic franchise before 2031.
5 min read Medicine
Behavioral Economics & Transit Policy
The zero price effect explains why politicians love free transit proposals. But making buses free might weaken the rider advocacy that protects service quality.
4 min read Economics
It Just Ain’t So
Are stock returns normally distributed? Formal normality tests reject this assumption for most equity indices, with major implications for risk management.
2 min read Finance
Not All AI Skeptics Think Alike
Apple's Illusion of Thinking paper found AI reasoning models collapse at high complexity. But critics argue the methodology, not the models, may be flawed.
2 min read AIGambling vs. Investing
Kalshi's CFTC-regulated exchange now offers sports betting nationwide. If you can bet on oil futures, why not NFL touchdowns? The line is thinner than you think.
2 min read FinanceThe Model Said So
LLMs excel at parsing market sentiment and writing reports, but finance demands audit trails and explainable decisions that black box models cannot provide.
1 min read FinanceDual Mandate Tensions
New NBER paper shows optimal Fed policy should partially accommodate tariff inflation, exposing a fault line in the dual mandate when prices and jobs conflict.
1 min read EconomicsBeyond Monte Carlo: Tensor-Based Market Modeling
UBS paper uses Transition Probability Tensors to bridge machine learning and arbitrage-free derivatives pricing, offering a faster alternative to Monte Carlo.
2 min read FinanceDeFi's $42 Billion Maturity Story
DeFi's institutional TVL hit $42B in 2024 as BlackRock launched its tokenized fund. Layer 2 dominance, bridge exploits, and MiCA regulation define the shift.
1 min read FinancePassive Investing's Active Problem
Research shows passive investing makes markets more volatile as index fund growth amplifies each trade's price impact while active managers lag behind.
2 min read FinanceThe Green Bond Commitment Premium
Pure-play green bond issuers see lower CO2 emissions, higher ESG ratings, and cheaper financing. Mixed issuers show no environmental benefit, research finds.
1 min read FinanceAlphaFold 3: Free for Science
Google released AlphaFold 3 for free, predicting molecular interactions beyond proteins. But is this generosity or a cloud platform play to own drug discovery?
1 min read AI
Against All Odds: The Mathematics of 'Provably Fair' Casino Games
Statistical analysis of 20,000 crash game rounds verifies the 97% RTP claim. But 179 rounds per hour means expected losses exceed 500% of wagers hourly.
4 min read Finance
Social Media Success Prediction: BERT Models for Post Titles
Training RoBERTa to predict Hacker News success revealed temporal leakage inflating metrics. How temporal splits, calibration, and regularization fix it.
5 min read AI
65% of Hacker News Posts Have Negative Sentiment, and They Outperform
Analysis of 32,000 HN posts reveals 65% negative sentiment correlates with 27% higher engagement. Six-model comparison, power-law distributions, full data.
2 min read AI
RSS Swipr: Find Blogs Like You Find Your Dates
Build an open-source ML RSS reader with swipe interface. Uses MPNet embeddings and Thompson sampling for personalized feeds that escape the filter bubble.
4 min read AI
Building a No-Tracking Newsletter from Markdown to Distribution
Build a privacy-focused newsletter with Python, Cloudflare Workers KV, and Resend API. Zero tracking, zero cost, full control. Open source code included.
4 min read Tech
Deploying to Production with AI Agents: Testing Cursor on Azure
Cursor AI deployed YOURLS on Azure via SSH in 15 minutes: server config, MySQL, SSL, and a custom plugin. Full transcript and tutorial available.
2 min read AI
Visualizing Gradients with PyTorch
Build the right mental model for gradients with this PyTorch visualization tool. 2D surface plots with gradient vectors show the direction of steepest ascent.
1 min read AI
Counting Cards with Computer Vision
How I trained a YOLOv11 model to detect playing cards at 99.5% accuracy and built a real-time Monte Carlo blackjack odds calculator using computer vision.
6 min read AI
Modeling Glycemic Response with XGBoost
A hands-on project predicting postprandial glucose curves with XGBoost, Gaussian curve fitting, and 27 engineered features from CGM data. Code on GitHub.
5 min read Medicine
Trading on Market Sentiment
GPT-3.5 matched RavenPack's 41% returns in a sentiment analysis trading strategy using 2,072 news headlines. See the full backtest results and comparison.
6 min read Finance
I Built a CGM Data Reader
Built a CGM data analysis tool with Python to visualize Freestyle Libre 3 glucose data alongside nutrition, workouts, and sleep for endurance cycling.
3 min read Medicine
Crypto Mean Reversion Trading
How I built a crypto mean reversion trading bot using PELT change point detection on Kraken, targeting altcoin price overreactions with automated execution.
3 min read Finance
My First 'Optimal' Portfolio
How I built Python portfolio optimization tools, tripled the Sharpe ratio from 0.65 to 1.68, and published the results as an academic paper on MPT.
2 min read Finance
The Tech behind this Site
A Hugo blog tech stack with Cloudflare R2 image hosting, responsive WebP shortcodes, Workers AI social automation, and GitHub Pages CI/CD deployment.
2 min read Tech