Viking Therapeutics stock jumps 33% on obesity shot data. The 22% and 97% figures need context

Shares of Viking Therapeutics (VKTX) jumped 33% to about $40.17 shortly before 10 a.m. ET on Tuesday, from a Monday close of $30.11, after the company reported results from a study of less frequent dosing for its obesity drug VK2735, according to Nasdaq data. Volume passed 16 million shares by about 9:55 a.m., against a daily average of about 2 million. Rivals Eli Lilly and Novo Nordisk were each down about 1%, a move Investor's Business Daily tied to the Viking data.

What Viking reported

In the roughly 180-patient trial, adults with obesity took weekly injections for 21 weeks, then switched to less frequent doses or placebo for 12 more weeks, according to Viking's release.

• After 21 weekly doses, weight loss ranged from about 16% to 19%, versus about 0% on placebo.
• Patients switched to every-other-week dosing kept up to 97% of that loss. Those switched to monthly dosing kept up to 90%.
• Stomach-related side effects during the 12-week maintenance phase were not meaningfully different from placebo, the company said.

Less frequent dosing is the commercial point. Viking, and obesity specialist Louis Aronne in a comment included in its release, argue that flexible schedules help patients stay on treatment. A proven monthly option would also give VK2735 a way to stand apart from the approved drugs the release names as its benchmarks, Lilly's Zepbound and Novo's Wegovy.

Reading the numbers carefully

The 22% headline comes from 13 people. Viking's release leads with "22% placebo-adjusted weight loss" at week 33. That figure comes from an exploratory control group of 13 patients who stayed on the weekly 17.5 mg dose throughout. They lost 21.7% from baseline, while placebo patients gained 0.3%. It is encouraging, with no plateau reported, but it is a small side arm, not the study's main question.

"Up to" means the best group. The 97% and 90% figures are the top results across several dose groups, not averages across all patients on each schedule. The text of the release reports only the top figures.

The comparison that matters is 61%. Patients moved from the drug to placebo still kept 61% of their weight loss after 12 weeks. So the real gap is roughly 61% versus up to 97%, or up to 90% for monthly. That is a clear separation, and Viking reported it as statistically significant, but 12 weeks is short for a treatment meant to last years.

This is not a pivotal trial. The study's formal goals were safety, tolerability and how the drug behaves in the body. Weight change was an exploratory endpoint. VK2735 is in Phase 3 studies for obesity, and those are the results regulators will weigh.

What traders are watching

Viking plans a second part of the study testing oral maintenance doses. The stock is now close to its 52-week high of $43.15, after trading as low as $24.52 over the past year, per Nasdaq. Moves this large on early-stage data can reverse as analysts work through the full results.

Sources: Viking Therapeutics; Investor's Business Daily; Nasdaq quote data around 9:53 a.m. ET. This is market information, not investment advice.