Taiwan memory chipmaker Nanya Technology hit a record month for sales, yet its stock sank — good news for the company's business, painful for investors who bought high.

• August sales set another record, up more than 560% from a year earlier on the AI-driven boom in memory chip prices.
• The stock opened higher, then reversed hard and closed near its low, breaking below the NT$500 mark.
• Sellers used the strong sales report as an exit, a classic sign that good news was already priced in.
• Small investors who tried to buy the dip got hit as the slide continued all day.

Outlook: The key questions now are whether Nanya can climb back above NT$500 and whether memory prices stay hot enough to justify the run-up.