Thai Oil will remain a highly strategic subsidiary of PTT, given high operational integration. Unfavorable industry conditions will hinder Thai Oil's earnings over 2020-2021 while high spending on the Clean Fuel Project will keep the company's debt-to-EBITDA ratio at about 8x in the period. We lowered Thai Oil's stand-alone credit profile to 'bb-' from 'bb'. On April 14, 2020, S&P Global Ratings revised its outlook on Thai Oil to negative from stable. We affirmed the 'BBB+' long-term issuer credit rating on the Thailand-based refinery. We also affirmed our 'BBB+' issue rating on senior unsecured notes Thai Oil issued or guaranteed. The negative outlook mirrors that of the local currency rating on PTT and reflects mounting pressure on PTT's creditworthiness, given