Oura, the smart-ring maker, has filed to go public, and the timing looks like a sale at the top — bad news for anyone buying into the IPO.

• Sales roughly doubled over the past year, but much of that came from a one-off viral surge in the spring that is unlikely to repeat.
• That spike means year-over-year growth will look great through early 2027 even if the business is already slowing.
• Costs are rising faster than profits, and the company has just enough cash and money owed to it to cover its bills.
• Only about two-thirds of paying users open the app daily, and yearly retention is 85% — people buy the ring, get their data, and drift away.
• Apple is expected to add heart-rate variability tracking to the Apple Watch, which would erase one of the ring's few unique selling points.

Outlook: IPOs like this usually price low, pop on day one, then bleed lower — expect the same here as growth cools and Apple moves in.