Saudi Arabia's benchmark index dropped 0.8%, with National Commercial Bank, the country's largest lender, falling 2% and Al Rajhi Bank down 0.7%.
Moody's on Tuesday affirmed ratings of all Saudi Banks, but changed outlooks to negative.
Clothing manufacturer Thob Al Aseel gained 3.3% after signing a 97.5 million riyals ($25.97 million) contract for medical supplies.
Meanwhile, Saudi Arabia's crude oil exports in May are expected to drop to about 6 million barrels per day, the lowest in almost a decade, and domestic refining output is likely to fall as the coronavirus crisis hits demand, Reuters reported citing industry sources and analysts.
Dubai's main share index retreated by 0.7%. Blue-chip developer Emaar Properties declined 2.3%, while budget airliner Air Arabia slid 3.7%.
Air Arabia, the only listed carrier in the United Arab Emirates, has laid off 57 employees due to travel disruptions caused by the coronavirus outbreak, a spokesman said on Tuesday.
The Abu Dhabi index fell 2%, dragged down by a 2.8% drop in the country's largest lender First Abu Dhabi Bank and a 2.4% fall in telecoms group Etisalat.
In Qatar, the index slipped 0.5%, hurt by a 1.9% fall in Qatar Islamic Bank.
Outside the Gulf, Egypt's blue-chip index bucked the trend to close 1% up. Commercial International Bank was up 1.5%.