October 28, 2026
Genmab shares exploded 29.3 percent, adding roughly 10 billion in market value in its biggest single day move in at least three years.
What happened
Genmab A/S saw its stock price jump 29.3 percent today. This single day move was larger than any the company has recorded over the past three years. The surge added roughly 10 billion dollars to the company's total market value.
Why it matters
A move of this size suggests a complete re-rating of the company's future, likely based on a clinical win, a major partnership, or a buyout offer. No other force in play from the broader market today explains a 10 billion dollar shift. The money flowing in is making a large, concentrated bet that the company's pipeline or revenue will be worth vastly more than it was priced yesterday.
The case against
A 29 percent spike on a single piece of news can be an overreaction if the event, while positive, does not add as much value as the new market cap implies. A binary outcome on a drug trial could have broken positively, but the resulting sales might take years to materialize and could still disappoint. The trading may also be driven by short sellers rushing to cover, temporarily exaggerating the price.
What settles it
The specific news release or regulatory filing from Genmab detailing the reason for the stock move.