Mumtalakat, Bahrain’s sovereign wealth fund, last month expanded its shares to become sole owner of the British McLaren Group. The sports car brand has been facing significant financial uncertainty and recently incurred substantial losses.

To Bahrainis, the move is a surprise given their country's own struggling economic climate—including an expected budget deficit of 8.2% of GDP through 2024. The International Monetary Fund (IMF) projects that the size of the island nation’s economy will...