Recently hitting new 52-week highs after posting strong Q4 results last Friday, investors may be wondering if it’s time to buy Delta Air Lines (DAL)  stock for more upside.As the largest domestic airline stock by market cap ($42.01 billion), Delta’s operational and financial performance has set the company apart from many of its main competitors such as American Airlines (AAL)  and Southwest Airlines (LUV) .Let’s see if higher highs are in store for Delta’s stock after achieving a record year in terms of re ...