China's most recognizable humanoid robot maker has just given investors a lesson in how fast a hot story can cool.

According to Reuters, shares of Unitree Robotics have fallen roughly 45% since their Shanghai debut on August 19, when the stock jumped more than fivefold. That slump cut the company's valuation from about $66 billion to roughly $36 billion — an on-paper loss of around $30 billion in a matter of days.

Reuters reports the reversal is fueling concerns that the robotics sector has inflated into a bubble. The pattern is a familiar one: a company with genuine name recognition lists into an enthusiastic market, early buyers bid the price to levels that assume years of flawless execution, and the correction arrives when reality reasserts itself. Note that even after the drop, Unitree is still worth far more than its IPO price implied — this is a retreat from euphoria, not a collapse.

The timing sits awkwardly against comments from the company's own chief executive. Unitree CEO Wang Xingxing has said humanoid robots still need substantial further development, and forecast that a significant breakthrough may take another five to ten years, according to a report carried by MSN. That is a long runway for a valuation built on the expectation of robots doing useful work at scale.

Unitree is best known for agile, relatively affordable quadruped and humanoid machines that have made it one of the most visible names in the field — which is exactly why its share price is being read as a proxy for the whole sector.

Why it matters: Unitree has become the market's thermometer for humanoid robotics, and a 45% drop just weeks after a fivefold pop suggests investors are starting to price the gap between impressive demos and commercially useful machines — a gap the company's own CEO says could take a decade to close.