Chip maker UMC had a wild trading day after its earnings call, and this is a mixed bag — strong underlying business, but investors are nervous about rising costs ahead.

• UMC's stock swung hard, dropping below a key level before bouncing back, as heavy selling met bargain buyers.
• Quarterly revenue hit a near-record high and chip shipments hit an all-time high, with factories running near full capacity and healthy profit margins.
• Profit still fell sharply because one-time investment gains from last year didn't repeat, dragging down the bottom line even though the core business grew.
• The company is spending billions more to expand factories in Singapore and Taiwan, which worries some investors about near-term costs eating into profits before the payoff arrives.
• Analysts remain upbeat long-term, expecting demand from phones, cars, and AI chips to lift prices and margins through 2027.

Outlook: Short-term the stock may stay choppy on cost worries, but analysts expect steady growth into next year and a bigger profit jump by 2027 as new factories and AI-related business ramp up.