United Airlines (UAL) shares have gained 16.8% on a year-to-date basis compared with the industry’s 11.5% growth. The S&P 500 composite index rose 15.5% in the same time frame, while the Zacks Transportation sector declined 4.7%. The Chicago-based company currently has a market capitalization of $15.85 billion.Upbeat passenger volumes, owing to the buoyant air-travel demand scenario, is the primary growth driver for UAL. The airline operator, presently carrying a Zacks Rank #2 (Buy), boasts an impressive tr ...