Amkor Technology's stock experienced a significant intraday plummet, dropping 8.25% during Friday's trading session. The semiconductor packaging and testing services provider faced substantial selling pressure as the session progressed.

The sharp decline followed the pricing of a secondary underwritten public offering of 10 million shares by the Kim family, significant shareholders in the company. Secondary offerings typically create downward pressure on stock prices due to investor concerns about potential dilution and increased share supply entering the market.

The offering was priced at $48.75 per share, representing a 5.5% discount to the stock's previous close and valuing the transaction at approximately $487.5 million. Following the sale, the Kim family will continue to own more than 49% of Amkor's common stock, maintaining their controlling interest. The selling stockholder has entered into a 180-day lockup agreement on its remaining holdings, and Amkor will not receive any proceeds from the transaction.