Key Highlights

  • SK Hynix had surpassed Samsung Electronics in memory sector market capitalisation heading into June 23, driven by its dominant position supplying HBM3E memory to Nvidia for AI accelerator chips.
  • Both Samsung and SK Hynix fell more than 12% on June 23 as South Korea's Kospi declined 10%, triggering global semiconductor contagion.
  • The Korean memory crash spread to US memory names Micron and SanDisk, both falling more than 13%, and swept the broader semiconductor supply chain lower.
  • SK Hynix's leadership in high-bandwidth memory had been the defining competitive dynamic in the memory sector entering 2026, with Samsung working to close the technical gap.

 

SK Hynix's remarkable ascent to surpass Samsung Electronics in memory semiconductor market capitalisation, driven by its commanding lead in HBM3E high-bandwidth memory production, provided essential context for understanding the severity of South Korea's June 23 market rout.

SK Hynix had established itself as the primary supplier of HBM3E memory to Nvidia, which integrates the chips into its H100 and successor AI accelerators. Each Nvidia AI chip requires multiple HBM3E stacks, and the enormous ramp in AI accelerator production had created a sustained period of supply constraint for HBM that allowed SK Hynix to extract premium pricing and extraordinary margins. That dynamic had driven SK Hynix's market capitalisation above Samsung's in the memory sector, reversing a long-standing competitive hierarchy.

Samsung had been working to close the HBM technical gap, qualifying its own HBM3E production with Nvidia and expanding its own AI memory capacity. The competitive dynamic between the two Korean giants had been one of the most closely watched stories in the semiconductor industry throughout 2025 and early 2026.

On June 23, both companies fell more than 12% as the Kospi declined 10%. The selloff reflected a reassessment of whether the extraordinary pace of AI-driven HBM demand could be sustained at current levels, given rising concerns about the financing of hyperscaler AI data centre buildout and the broader question of AI capital spending sustainability. Forced selling from leveraged positions in Korean memory equities amplified the directional move.

The contagion spread immediately to US markets, with Micron Technology and SanDisk each falling more than 13% as investors reduced exposure to the entire global memory supply chain.