A Professor Kept His Day Job for 13 Years. His IPO Just Broke a Record.

On May 27, 2026, a small Chinese fiber-optics maker called Changjin Photonics (688635.SH) went public on Shanghai's STAR Market. Its IPO price was RMB 40.98. It opened at RMB 628.88 — already up over 14x — and closed the day up 1,510%, an all-time record for a first-day A-share pop. Anyone lucky enough to win a single IPO lottery allotment (500 shares) was sitting on roughly RMB 266,000 (~$37,000) in paper gains by the closing bell.

The company behind the fireworks has 254 employees and made less than $14M in net profit last year. Its chairman, Li Jinyan, didn't formally leave his university faculty position until July 2025 — thirteen years after founding the company in 2012.

Li's path is unusual even by China's "professor-entrepreneur" standards. He did his PhD at the Shanghai Institute of Optics and Fine Mechanics, then spent years as an R&D engineer at Fiberhome (one of China's largest fiber-optic firms) before returning to academia at Huazhong University of Science and Technology's Wuhan National Laboratory for Optoelectronics. He started Changjin Photonics on the side in 2012, running it in parallel with his professorship for over a decade before the company went public.

What does it actually make? Rare-earth-doped optical fiber — ordinary fiber carries light signals, but fiber doped with erbium, ytterbium, or holmium ions can amplify light or convert electricity into a laser beam. It's the core component inside fiber lasers (used in precision metal cutting and aerospace manufacturing) and erbium-doped fiber amplifiers, which are essential for transoceanic fiber cables — without them, signal loss over long distances would make undersea internet cables impractical.

Revenue from this single product line makes up over 85% of the company's business: RMB 145M in 2023, growing to RMB 247M in 2025, with net profit rising from RMB 55M to RMB 96M over the same period. Modest growth — but the market didn't price it like a modest company. On IPO day, its market cap briefly hit RMB 61.8 billion (~$8.7B), implying a P/E ratio over 600x.

Why? Because almost no other Chinese company can mass-produce high-quality rare-earth-doped fiber at scale — the field is otherwise dominated by a handful of US, Japanese, and European firms. In a market obsessed with "domestic substitution" of foreign-controlled tech, Changjin was effectively the only pure-play stock available. Two days later the stock hit a fresh high of RMB 749.85 (+1,730% vs. IPO price, ~RMB 70B market cap) before swinging violently — by June 8 it had pulled back to RMB 566.66, still up over 13x from the IPO price.

This is a simulated-portfolio research note based on public disclosures, not investment advice. Markets carry risk.