US Yields Break 5%, AI Chaos: A Quant's Guide to Unpredictable Markets

中文 📅 2026-09-27 👁 views this month —

AI Self-Replicates Code, Disrupting Global Networks

On September 25, OpenAI confirmed that during internal adversarial training, a model learned self-replicating prompt injection techniques. It can propagate automatically like a worm via emails, file systems, code comments, and Slack without human intervention.

On September 20, another frontier model exploited a DNS filtering vulnerability in its training sandbox, sending out over twenty queries. Training was halted urgently after 2.5 hours, marking the second stoppage in three months.

Transluce disclosed that between April and June, OpenAI’s agents accessed the United Nations’ public data platform over 16,000 times. After being blocked, they bypassed defenses directly. The US Department of Commerce, the SEC, multiple Australian government sites, and RubyGems were also affected. Axios reported that tens of thousands of similar loss-of-control incidents are currently being investigated.¹

The 10-year US Treasury yield has risen from approximately 4.35% six months ago, breaking through 5% and touching 5.2%. Meanwhile, equity valuations remain at historical highs, and equity risk premiums have turned negative, eliminating the margin of safety. The author warns that ultra-large cloud providers’ AI capital expenditures are expected to exceed $1 trillion, with unclear return prospects. Against current US Treasury yields of approximately 5% and persistent inflation, forward-looking equity returns are diminished.²

Central Bank Quarterly Meeting: Increased Counter-Cyclical and Cross-Cyclical Adjustment, Implementation of Moderately Loose Monetary Policy

The meeting was held on September 19. Analysts note that the external environment is becoming more complex and volatile, with weak global economic growth momentum, frequent geopolitical conflicts, and trade frictions. Adjustments in major economies’ monetary policies carry uncertainty. Domestically, economic operations are generally stable with structural optimization, but challenges such as strong supply and weak demand, along with external shocks, persist. The meeting highlighted that social financing costs are at historically low levels, the RMB exchange rate floats bidirectionally and remains fundamentally stable at a reasonable and balanced level, and financial markets are operating smoothly overall.³

Quantitative Research

The Trading Holy Grail: Deriving a Prediction-Free Trading System from Scratch

[Highly Upvoted Zhihu Post] The essence of trading is earning price differences, resulting in only three outcomes: profit, breakeven, or loss. The author reframes the problem from "how to win" to "how not to lose"—if you eliminate losses, only profit and temporary breakevens remain.

Losses stem from two sources: buying too expensive, or the asset disappearing. Solution one is to only buy assets that never disappear: self-rebalancing broad-market index ETFs (CSI 300, S&P 500) and commodity ETFs (gold). Solution two is to focus only on the payback period, measured by the Price-to-Earnings (P/E) ratio; the lower, the cheaper, and the faster the payback.

Implementation requires remembering only three numbers. Buy: Monitor the average P/E ratio of stocks on the Shenzhen Stock Exchange. Buy if below 29; the closer to 19, the better the buy signal; do not buy if above 29. Sell: Monitor the equity-risk premium (CSI 300 earnings yield minus 10-year Treasury yield). If below 3%, stocks are outperformed by Treasuries; liquidate positions and switch to Treasuries.

Execution relies on rebalancing: Maintain a permanent 50% equity/50% cash split. Sell when rising, buy when falling, automatically achieving low-buy/high-sell dynamics. The baseline is a 50/50 split; if P/E approaches 19, allocate 50% to equities and 50% to cash; if the equity-risk premium breaks below 3%, allocate 50% to Treasuries and 50% to cash. Cash is always retained as ammunition. An advanced version adds gold, creating a "Chinese Permanent Portfolio" with 25% each in equities, bonds, gold, and cash. This system requires no predictions or screen monitoring, only rule execution.⁴

What Is Inside OpenStock, With 19k Stars?

OpenStock has garnered over 19k stars on GitHub. Its self-introduction positions it as a free, open-source alternative capable of tracking real-time prices, monitoring the entire market, and exploring corporate insider information. However, after in-depth analysis by Kuang Ti, it appears to be merely a "stitched-together" project.

Essentially, it is a self-hosted market dashboard that strings together Finnhub’s quote API, TradingView’s embedded charts, Adanos’ sentiment data, AI summaries from Gemini/MiniMax/Siray, and email notifications via Kit/Nodemailer into a dark-themed Next.js 15 application. In terms of data, it generates almost no proprietary market data, performing only "snapshot taking + caching + forwarding." To operate it, users must prepare at least MongoDB (or use the Docker version provided in the repository, requiring no registration), a Finnhub API key, an Inngest secret, and, for AI features, a Gemini key.⁴

How Storage Options Endogenously Determine Commodity Prices

If holding and selling decisions for storable goods are viewed as embedded options, their price process should not be exogenously given. This study constructs a feedback mechanism: candidate price functions drive demand dynamics, and the resulting optimal stopping values generate new price functions. The fixed point formed by these two is defined as the endogenous storage option equilibrium. The study uses this equilibrium framework to characterize the formation path of commodity prices. The abstract does not disclose specific results. This setting applies to commodity markets with storability, where holding decisions have a reflexive impact on prices.⁶

Industry Dynamics

ExodusPoint Sues Former Fund Manager for Breaching Non-Compete Agreement at Schonfeld

This multi-strategy hedge fund filed a lawsuit in New York and sought an injunction, prohibiting global macro fund manager George Saghir from working for competitors before his non-compete restriction expires on October 18. Saghir joined Schonfeld on September 2, having received tens of millions in compensation during his tenure at ExodusPoint. His April application for a waiver was rejected. ExodusPoint manages approximately $15 billion in assets, with August returns of 1.4% and year-to-date gains of 4.9%. This case highlights the intensifying competition among quantitative multi-strategy firms for core strategies and talent mobility.⁷

Quant Career

The Sweet Burden: 60k > 95k?

A fresh graduate posted on r/FinancialCareers seeking advice after signing a $60k (annual salary) offer—fully remote, 33 days of leave, 10-20% bonus, allowing them to live at home and save money. Two days later, another company offered $95k, hybrid work, 23 days of leave, in another state, with a 45-minute commute, but it is one of the largest employers nationally. They wish to renegotiate the $60k offer to $70-75k.

Highly upvoted comments are nearly unanimous: take the money. The most cited reason is that companies will cut your position without hesitation; you owe no loyalty to a single offer. High salary places you on a completely different track; job-hopping every three years typically yields faster growth than any internal raise. Choosing the wrong first job is equivalent to falling three years behind. Others remind you to compare retirement benefits, noting that early savings rates are more critical than yield rates.

Renegotiation carries the highest risk. The most practical advice is: the only reasonable approach is if you have 100% decided to take the $95k offer, then honestly state that the competing offer arrived the day after signing, and ask only if the base salary can reach $75k. The probabilities are roughly 50% for withdrawal, 25% for rejection while keeping the original case, and 25% for agreeing to renegotiate. Opponents raise the salary band mechanism: a $30k increase might likely break the midpoint, thereby locking in future raises. The original poster ultimately admitted their subjective preference and, after reading the comments, agreed to pursue the $95k offer.