About Me

Hey, I’m Zhang Hangyu (Zhy) — a software developer and data analyst by background, and an individual investor.

This blog is where I’ve been writing for a while. It started out mostly about Python and data analysis; these days the focus has shifted to US equity research and trading systems. I still write about technical work — it just changed from “what I learned” to “what problem I solved with it.”

What I write about here

• US equity research — semiconductors, storage, AI infrastructure; earnings and Investor Day reviews
• Real trade reviews — including the ones I got wrong
• Position sizing and risk management — core vs. event positions, scaling out, trading discipline
• AI automation — using AI and self-hosted services to solve my own problems
• Software and data practice — Python, Docker, data analysis

About the investing posts

These posts document my own research, judgment, real trades and the way my trading system evolves.

I’m not a licensed investment advisor, and none of this constitutes investment advice. Details of my actual positions are anonymized; price levels cited are public market data.

I’m especially willing to write up the cases where I got the direction right but the execution wrong — or simply lost money. Those are the most useful posts for me, and I suspect for readers too.

Get in touch

If you disagree with something I wrote, or spot a factual error, please leave a comment under the post — I’d rather hear the counterargument than the agreement.

Email: mail@zhanghangyu.com