Mubasher: Moody's Investors Service expected the fiscal and external constraints in the GCC to persist beyond 2016, according to a report.

GCC countries' institutional strength will determine their ability to push through economic and fiscal reforms designed to counter the drop in oil revenue, according to the rating agency.

Moody's review concluded with a downgrade of three GCC sovereign ratings, and a negative outlook assigned to four countries that were confirmed.

“Moreover, the social impact of fiscal reforms will make policy implementation tougher for Bahrain (Ba2 negative), Oman (Baa1 stable) and Saudi Arabia (A1 stable),”  Moody's said, adding that “In comparison, Kuwait (Aa2 negative), Qatar (Aa2 negative) and the United Arab Emirates (UAE, Aa2 negative) have fewer such constraints.”

Qatar and the UAE have high institutional strength scores. Bahrain and Oman's scores rank toward the middle, while Kuwait and Saudi Arabia's scores are weaker.