SK Innovation Co.: The South Korean oil refiner swung to a net loss in the second quarter due to weaker refining margins and lower oil prices amid sluggish demand caused by the pandemic.

Smith & Nephew PLC: The U.K. medical-technology company turned a pretax loss for the first half of the year and said trading profit missed consensus expectations as the pandemic hurt its margin.

Solvay SA: The Belgian chemical company reported a fall in second-quarter net profit as the pandemic hurt demand in several sectors. Solvay expects a challenging third quarter before trading starts to improve in the fourth quarter.

Sumitomo Mitsui Financial Group Inc.: The Japanese financial company said its first-quarter net profit fell 60% from a year earlier due partly to greater provisions for possible loan losses amid the pandemic.

Wizz Air Holdings PLC: The U.K. airline reported a pretax loss for the first quarter of fiscal 2021 due to the pandemic.

Write to Rose Manzo at Rose.Manzo@wsj.com and Shayna Sebold at Shayna.Sebold@wsj.com