A $40 billion selloff in a 141-year-old Japanese cable firm has served as a reality check on the fragility of the global artificial intelligence-driven stock rally.

Optical fiber cable maker Fujikura almost halved in value in the week through May 20 as investors rushed to dump its stock following a disappointing earnings forecast and lackluster medium-term plan. While the shares have since recouped some of those losses, they¡¯re still trading almost 30% below their all-time closing high hit on May 13.

Fujikura¡¯s roller-coaster week reveals how quickly the tides can turn for AI stock winners as investors realize hopes for explosive growth in infrastructure may have run far ahead of manufacturers¡¯ ability to deliver.