Viking Therapeutics (NASDAQ:VKTX) saw its shares surge more than 24% in premarket trading on Tuesday, September 22, 2026, after the company unveiled new maintenance data for its experimental obesity drug, VK2735. The stock was trading at $37.30 by 08:54 EDT, up sharply from Monday's close of $30.11. The rally added roughly $839 million to the company's implied equity value, a significant move that underscores investor enthusiasm for the obesity treatment space.
The catalyst was a topline release detailing results from a 12-week maintenance phase of a clinical trial. Patients who received monthly doses of VK2735 maintained 85% of the weight loss they had achieved during the initial 21-week treatment period. Meanwhile, those on an every-other-week schedule preserved 90% of their prior weight loss. The data suggests that less frequent dosing could be a viable option for long-term weight management, potentially improving patient convenience and adherence.
The market's reaction was notably company-specific. While Viking shares climbed, major competitors Eli Lilly (NYSE:LLY) and Novo Nordisk (NYSE:NVO) both slipped in premarket trading, with declines of about 1.1% and 0.7%, respectively. This divergence indicates that the positive news was isolated to Viking, rather than a broad sector rally.
Breaking down the maintenance results, the every-other-week group maintained between 83% and 97% of weight loss across dose cohorts, while the monthly group retained 82% to 90%. Safety profiles during maintenance were comparable to placebo, with adverse events reported in 38% of every-other-week patients and 49% of monthly patients. Early discontinuation rates were low, at 3% and 5%, respectively.
Viking's CEO, Brian Lian, highlighted the potential for higher doses in future studies, noting that the results "may provide an opportunity to evaluate additional higher doses." However, he emphasized that further controlled trials would be necessary to explore this option.
In a separate exploratory weekly dosing arm, patients achieved approximately 22% weight loss by Week 33, with weight loss still not plateauing, according to the company. This suggests the drug's efficacy could be even more pronounced with continued treatment.
The company's injectable Phase 3 programs, VANQUISH 1 and 2, were fully enrolled in July, and an oral Phase 3 study is still slated to begin in the fourth quarter. These milestones will be critical for advancing VK2735 toward potential regulatory submission.
Financing remains a counterweight to the optimism. Viking held $502 million in cash and investments as of June 30, while second-quarter research spending reached $115.8 million. The company's burn rate suggests it may need additional capital to fund its late-stage trials, though the recent stock surge could provide a favorable window for raising funds.
Analyst targets, which were set before Tuesday's data, point to significant upside. JPMorgan's Hardik Parikh has an Overweight rating with a $65 target, implying 74.3% upside from the premarket price. Canaccord Genuity's Edward Nash set a $114 target (205.6% upside), and Lake Street Capital's Daniel Brims has a $89 target (138.6% upside). These figures, however, do not incorporate the latest readout, so they should be viewed with caution.
Risks remain, including the small size of maintenance cohorts, one excluded monthly outlier, and rising trial costs. The next major test will be the oral Phase 3 initiation in the fourth quarter, which investors will watch closely to see if the momentum continues.
