Moody's Investors Service ("Moody's") changed Diamondback Energy, Inc.'s (Diamondback) rating outlook to positive from stable, and simultaneously affirmed the company's Ba1 Corporate Family Rating (CFR), Ba1-PD Probability of Default Rating (PDR), and Ba2 senior unsecured notes. "The positive outlook acknowledges Diamondback's significant production, reserves and free cash flow growth visibility through 2021 even in a sub $50/bbl oil price environment," noted Sajjad Alam, Moody's Senior Analyst.