Taiwan's three big container shipping companies are surging as shipping rates stay high, which is good news for their investors but a warning sign for anyone paying to move goods.

• Wan Hai, Yang Ming, and Evergreen all jumped last week, with Wan Hai hitting its daily limit and gaining the most.
• Rates are staying high because shipping capacity is squeezed from several directions at once.
• Typhoons shut some Asian ports, low water in the Panama Canal and the Rhine slowed traffic, European dock strikes added delays, and the US-Iran conflict is tying up ships.
• Delays mean empty containers come back slower, which keeps rates propped up.
• Foreign investors piled in hard last week, buying all three names in size.

Outlook: Rates should hold up through the busy third quarter and any fourth-quarter pullback is expected to be gradual, unless the Red Sea and Hormuz routes reopen — but the stocks look stretched once they trade above book value.