Viking's stock has tripled in less than a year, and its red-hot valuation could have investors thinking twice about buying it today.Viking Therapeutics (VKTX 7.09%) has been one of the hottest healthcare stocks to own this year, thanks to hype and excitement relating to its promising weight loss treatment, VK2735. The potential that investors see in the drug is a key reason the stock has ballooned to a market cap of nearly $6 billion despite the company generating no revenue and having no approved products ...