Why Amkor Stock Jumped on a $1.3 Billion Nvidia Deal in South Korea, Then Gave It Back

Amkor Technology stock rose 3.61% in the first minute after the chip packaging company announced a $1.3 billion agreement with Nvidia to expand its factories in South Korea, an announcement that reached the MoveSurge news feed at 07:30:00 ET on Wednesday, October 21, 2026. AMKR went from $44.88 to $46.50 in premarket trading, but the gain faded: at 10:25 ET the stock was at $43.16, up 3.49% from Tuesday's close of about $41.70, according to Yahoo Finance.

The deal was part of a wider plan Nvidia announced the same morning at its GTC conference in Berlin, where it named six suppliers that will add capacity for its AI chips. Nvidia's announcement came out before Amkor's own release. At $44.88 a minute before Amkor's release, the stock was already about 7.6% above Tuesday's close.

What the Amkor and Nvidia deal covers

Amkor puts a finished chip into a package that connects it to the rest of a computer. For AI processors this includes an interposer, a thin layer that links the processor to its stacks of high-bandwidth memory. Under the plan, Amkor will raise its interposer wafer capacity in South Korea by more than 300% by the end of 2028. Amkor said Nvidia's prepayments under the $1.3 billion agreement will match its factory capacity to Nvidia's long-term needs for advanced packaging.

Nvidia's plan reaches across its supply chain. Substrate makers IBIDEN, Samsung Electro-Mechanics and Unimicron are expected to raise capacity for the base boards that chips are mounted on by 2.5 times over three years. Chip testing company KYEC received an advance to build new test sites in the United States, with high-volume production planned for April 2027. Amkor reports its own third-quarter results on October 26.

How the stock traded

One minute after the release, Amkor was at $46.50, up 3.61% from the minute before, and that minute's high was $46.87, about 12.4% above Tuesday's close. The one-minute candles on the chart above show a different first-minute price, $45.10, up 0.49%, because the chart reads the candle that contains the headline. Both readings agree on what followed: the next candle gave back most of the spike, and the price was $45.69 fifteen minutes after the release, up 1.80% from the pre-release level. When regular trading opened, the stock fell further, to $43.16 by 10:25 ET.

Amkor's first Nvidia deal this year also drew a sharp first reaction. On July 23, 2026, the two companies signed a $1.5 billion agreement, with an Nvidia prepayment, to expand Amkor's packaging and test capacity in Arizona. The stock jumped 17% in extended trading that evening, according to Reuters, and traded at $76.05 at 17:04 ET in our data. At $43.16 on Wednesday, it was about 43.2% below that price.