On April 6, 2026, the South Korean stock market witnessed an extraordinary surge in optical communication stocks, with Daehan Kwangtongshin (Daehan Optical Communication) at the center of the rally. The company’s shares soared to a new 52-week high, closing at 14,730 won—a staggering jump that capped off a month of relentless gains and placed the stock firmly in the spotlight of both domestic and international investors.
According to Hankyung, Daehan Kwangtongshin’s meteoric rise is no isolated event. Over the past three months, the company’s share price has quadrupled, fueled by a perfect storm of technological shifts, global investment trends, and mounting anticipation around artificial intelligence (AI) infrastructure. The numbers speak for themselves: as of April 6, foreign investors had accumulated a net purchase of 6,968,000 shares over the past month, while institutional investors sold off 6,148,000 shares and individual investors shed 1,322,000 shares. During this period, trading volume was dominated by foreigners and individuals, accounting for 17.4% and 79.4% of activity, respectively.
April’s opening week provided a dramatic showcase of this trend. As reported by Econonews, Daehan Kwangtongshin’s shares surged by 13.89% in early trading on April 6, reaching 14,510 won, and then climbed further to 14,730 won by 9:44 a.m. as noted by Global Economic and Money Today. This sharp ascent followed a series of remarkable gains: the stock hit its daily upper limit on April 1, then jumped 7.55% and 25.89% on April 2 and 3, respectively. In just over a month, from February 27 to April 3, the company’s share price rocketed from 4,295 won to 12,740 won—an eye-popping 196.62% increase.
The rally in Daehan Kwangtongshin and its peers is part of a broader global shift toward optical communication technologies, driven by the exponential growth of AI-related data. As Maeil Business Newspaper reports, March saw a significant pivot among investors, many of whom moved out of traditional semiconductor stocks and into optical communication plays. The reason? The world’s AI giants—Amazon, Google, Meta, and Microsoft—are expanding their data centers at breakneck speed, and the sheer volume of data being shuttled between high-performance graphics processing units (GPUs) is overwhelming conventional copper wire connections. Optical communication, which converts electrical signals into light and transmits them through ultra-thin glass or plastic fibers, offers a solution by delivering higher bandwidth, lower latency, and improved energy efficiency.
“Optical communication is a long-term investment theme because it can send more data, faster, while reducing power consumption and heat,” one early adopter told Maeil Business Newspaper. Investors like him have flocked to U.S. companies such as Lumentum and Coherent, which produce the high-speed lasers, optical components, and transceivers that make AI data centers possible.
Jensen Huang, CEO of NVIDIA, underscored this global pivot at the GTC 2026 conference in March, announcing plans to invest $2 billion each in Lumentum and Coherent. According to Global Economic and Money Today, Huang’s endorsement and the subsequent investments have turbocharged the optical communication sector, both in the U.S. and abroad. Lumentum’s sales are projected to leap from $1.645 billion in 2025 to $2.91 billion in 2026, with a net profit margin expected to reach 22.8%. Coherent, meanwhile, is forecast to generate sales of 10.4 trillion won in 2026, with an anticipated net margin of 15.1%.
The ripple effects have been felt in Korea, where Daehan Kwangtongshin and other local optical communication stocks like LS Eco Energy and Oi Solution have seen their shares outperform the broader market. Daehan Kwangtongshin, in particular, has been buoyed by several factors. As detailed by Hankyung, the company is vertically integrated, manufacturing both optical cables and fibers from raw materials to finished products. This verticalization is seen as a strategic advantage, especially after Daehan Kwangtongshin secured a major order for ultra-high-density cables for data centers in February—a move that marked its entry into the premium market and raised expectations for further contracts with global tech giants.
The government’s recent announcement of a national strategy to advance digital infrastructure and target 6G commercialization by 2030 has further fueled investor optimism. As Seoul Wire reports, the government aims to strengthen core infrastructure in networks, data, and cybersecurity between 2026 and 2028, positioning Korea as one of the world’s top three AI powers. Telecom giants LG Uplus and LG Electronics have also joined forces to develop AI-based communication technologies and pursue international standardization. These moves have provided additional momentum to sector stocks, with Daehan Kwangtongshin gaining 16.17% in early trading on April 6, alongside other communications equipment makers.
Yet, amid the euphoria, some analysts caution that the sector’s rapid ascent has already priced in much of the anticipated growth. Daehan Kwangtongshin posted sales of 139.4 billion won in 2025 but recorded a net loss of 28 billion won. Even if the company achieves the projected net profit of 18.2 billion won in 2028, its forward price-to-earnings ratio (PER) would still be a lofty 108, according to Hankyung. The story is similar for other Korean optical communication stocks, which, despite projected modest profits in 2026, remain expensive by traditional valuation metrics.
This high valuation risk is not unique to Korea. U.S. optical communication leaders Lumentum, Coherent, and Ciena have all experienced surging share prices, but their PERs remain elevated—Lumentum’s is expected to drop to 91 by mid-2026, Coherent’s to 44, and Ciena’s to 64, as reported by Maeil Business Newspaper. These figures reflect both the promise and the peril of investing in a sector at the heart of the AI revolution.
For investors wary of picking individual winners in a volatile market, exchange-traded funds (ETFs) have emerged as a safer alternative. The newly launched KODEX U.S. AI Optical Communication Network ETF, for example, concentrates on the sector’s U.S. heavyweights and has attracted over 50 billion won in inflows within a single day. Still, experts warn that these funds are not without risk: the underlying companies are only just beginning to see profits, and dividend yields remain low.
Ultimately, the surge in Daehan Kwangtongshin and its global peers is a testament to the seismic changes underway in the world’s data infrastructure. As AI continues to reshape industries, the demand for faster, more efficient data transmission will only grow, keeping optical communication companies in the crosshairs of investors and tech giants alike. But with high valuations and intense competition, the road ahead is likely to be as volatile as it is promising.