The huge demand for effective new weight management drugs has billionaire investors feeling bullish about this stock.Wall Street investment banks keep pounding the table on Viking Therapeutics (VKTX -2.27%) and its weight loss drug candidate. Predictions vary, but the average analyst who follows the stock thinks it can rise 98% from recent prices.Investment bank analysts aren't the only folks on Wall Street who think the clinical-stage biopharma has a bright future. In the second quarter, billionaire money ...