Viking Therapeutics' oral obesity drug meets mid-stage study goal, shares fall

** Shares of drug developer Viking Therapeutics VKTX.O fall 18% to $33.96 premarket

** Co says its experimental oral obesity drug, VK2735, showed statistically significant reductions in body weight compared with placebo and was safe and well-tolerated through 13 weeks of daily dosing

** Co says the drug helped patients lose 12.2% of their body weight on average over 13 weeks

** Analysts ahead of the results had expected weight loss in the range of 10% to 15% on average and greater than the 8.2% seen in a small early-stage trial

** Co says 13% of participants receiving placebo discontinued treatment due to side effects, compared with 20% of participants receiving VK2735

** Up to last close, stock was up 4.6% YTD