These are some of the stocks making the biggest moves during midday trading: Viking Therapeutics — Shares tumbled 42% after phase 2 trial results showed Viking's experimental oral obesity drug had more side effects than expected. About 20% of the patients in the trial quit using the drug due to symptoms such as nausea and vomiting. On average, patients lost 12% of their starting weight after 13 weeks. Target Hospitality — The temporary workforce housing play jumped 6.8%. On Monday, Stifel upgraded Target Hospitality to buy from hold, dubbing it a "back door data center play" and lifting its target price to $11 from $7.50. The new target price suggests about 37% upside from Monday's close. Nvidia , Advanced Micro Devices and Palantir Technologies — Investors took profits in some of this yea

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