AI Infrastructure Leader Loses 9 Trillion Won in Market Cap in Just One Day Despite Strong Earnings

Ciena Corp (CIEN) saw its shares plunge 9.69% on the New York Stock Exchange on June 5, closing at $483.74. Its market capitalization stood at approximately $68.4 billion (roughly KRW 105 trillion), wiping out about $6 billion (around KRW 9 trillion) in value in a single day.

In its fiscal 2026 second-quarter earnings report released the previous day, Ciena posted revenues of $1.57 billion (about KRW 2.4 trillion) and an adjusted EPS of $1.64, both ahead of market expectations. It also raised its full-year revenue guidance to $6.3 billion (approximately KRW 9.7 trillion). However, the increase fell short of analysts’ forecasts, triggering a classic “buy the rumor, sell the news” sell-off.

After a more than 120% rally since the start of the year—pushing the stock to an 18-year high—profit-taking combined with a broader sector correction to drive shares down by around 10%.

Headquartered in Maryland, Ciena provides optical transport equipment and communication network solutions, supplying high-speed optical networking gear to global carriers, cloud service providers and major data centers.

With surging AI compute demand fueling investment in ultra-high-speed data-center interconnects, Ciena has emerged alongside Nvidia as a leading beneficiary of the AI infrastructure boom in the U.S. market.