[Reporter's Notebook] After years of billion-dollar licensing deals, Korea’s biotech boom faces its reckoning.

A sharp sell-off in two of Korea’s most prominent biotech stocks exposed growing investor impatience with opaque royalty terms, milestone-heavy deals and the gap between projected valuations and realized cash flow. (Image generated by OpenAI)

For years, Korea’s biotech sector has announced licensing agreements valued in the trillions of won, figures that can translate into hundreds of millions or even billions of dollars. The totals were often celebrated as validation that Korean platforms could compete globally.

In January, investors began asking a different question: how much of those headline sums would actually materialize.

The reassessment was swift. On Jan. 21, shares of Alteogen, the developer of the ALT-B4 subcutaneous drug delivery platform and then the largest company on the tech-heavy Kosdaq market, fell more than 22 percent in a single day.

Investors focused on a detail in regulatory filings by MSD, known as Merck & Co. in the United States and Canada. The royalty rate tied to Keytruda Qlex, a subcutaneous version of the cancer drug pembrolizumab that uses Alteogen’s hyaluronidase-based drug-delivery technology, was about 2 percent, below the 4 to 5 percent many in the market had assumed.

Within two trading sessions, roughly 6 trillion won ($4.2 billion) in market value had disappeared. Alteogen has since slipped to second place on the Kosdaq by market capitalization.

Nine days later, shares of ABL Bio, the biotech that licensed its Parkinson’s candidate ABL301, a bispecific antibody incorporating its Grabody-B blood-brain barrier shuttle platform, to Sanofi in a deal once valued at more than $1 billion, fell nearly 20 percent. Sanofi had described the program as “deprioritized” within its research pipeline.

The agreement remained intact, the asset was not returned and development was not formally terminated. But the signal unsettled investors.

Neither company reported a failed clinical trial. Neither lost regulatory approval. Both confronted something subtler: a market less willing to price in optimistic assumptions.

The turbulence comes at a paradoxical moment. As the Kosdaq index climbed above 1,000 this year, signaling renewed appetite for growth stocks, biotech shares lagged. The broader market was rallying. Biotech was recalibrating.

The reasons extend beyond one royalty rate. Alteogen’s preliminary 2025 earnings showed revenue of 202.1 billion won ($141 million), more than double the previous year, and operating profit rising nearly 275 percent.

Analysts in mid-February reiterated buy ratings, pointing to accelerating commercialization of subcutaneous reformulations of intravenous blockbusters and to favorable developments in patent litigation involving Halozyme, the U.S. drug delivery company that develops competing hyaluronidase-based enzyme technology. Some analysts projected additional platform licensing deals in 2026.

The controversy was not about clinical efficacy. Keytruda Qlex secured U.S. FDA approval last year and has since moved into commercial rollout in the United States, clearing a key step toward hospital adoption. The issue was transparency.

Although MSD’s third-quarter regulatory filing in November referenced the royalty framework, Alteogen initially declined to confirm details publicly, citing confidentiality provisions. The company later said it had been in discussions with MSD regarding the disclosure and expressed regret that it had not communicated more clearly or quickly.

The contract did not change. The market’s tolerance for ambiguity did.

Investors were reminded how milestone-heavy biotech agreements function. A licensing deal may be announced as worth hundreds of millions or billions of dollars, but only a small portion, often less than 10 percent, is paid upfront. The remainder depends on regulatory approvals, commercial milestones and long-term sales performance. Those conditions may take years to satisfy, if they are met at all.

This structure is standard in global drug development. In Korea’s retail-driven equity market, however, aggregate deal values have often dominated investor psychology more than payment timing or royalty mechanics.

The same pattern is visible elsewhere. Medical AI company Lunit recently announced a 250 billion won rights offering, equivalent to more than 20 percent of its market capitalization, to reduce pressure from convertible bonds issued during its acquisition of New Zealand-based Volpara Health. Over the past three years, Lunit has raised roughly 450 billion won in equity capital. Management described its fundamentals as solid. Investors focused on dilution.

Even corporate governance changes introduce uncertainty. Alteogen said Monday that it plans to transfer its listing from the Kosdaq to the main Kospi board as early as the third quarter of this year.

The move could broaden institutional ownership. But index mechanics complicate the transition. Funds tracking the Kosdaq 150 would be required to sell upon departure, while inclusion in the larger Kospi 200 would depend on maintaining a high market value ranking during an initial 15-trading-day window. Analysts say volatility during that period could delay automatic buying by index funds until the next rebalancing in December.

Meanwhile, ABL Bio’s case illustrates another structural reality of platform biotech. Licensing partnerships do not guarantee strategic control. Sanofi’s portfolio adjustments may affect the timing of ABL301’s development without altering the underlying Grabody-B shuttle technology, which is designed to transport therapeutic antibodies across the blood-brain barrier.

The platform has also attracted multi-billion-won partnerships with GSK and Eli Lilly for central nervous system applications. Analysts continue to view the scientific premise as intact.

For more than a decade, Korean biotech sought validation through global licensing deals. The strategy brought capital, credibility and, in some cases, regulatory approvals.

It now faces its second phase: commercialization scrutiny.

The question in Seoul is no longer whether the science works, but when it will generate cash. Investors are examining royalty rates, patent terms and milestone structures, focusing on the timing of revenue rather than peak-sales projections.

That shift comes as the broader market has tried to narrow what investors call the “Korea discount,” the persistent gap between Korean stock valuations and those of global peers, through governance reforms and tighter disclosure standards.

Biotech, perhaps more than any other sector, depends on trust. Drug development is probabilistic. Licensing contracts are conditional. Regulatory pathways extend over years.

The boom has not ended. Approvals have been secured, and multinational drugmakers are still signing deals. But in 2026, investors are asking for less emphasis on total contract value and more clarity on the path to payment.