Arrest of billionaire Saudi prince shines light on U.S. holdings: Citigroup, Twitter, Apple

The risk to financial markets is more about political unrest and instability in Saudi Arabia, rather than a dramatic drop to Prince Alwaleed's U.S. stock holdings, like Citigroup, which he has owned since 1991, and Apple.

"The risk for global markets is that the Saudi royal family destroys itself in a fratricidal game of thrones, opening the door to a new radical regime that would be hostile to U.S. interests or play games with oil supplies," said Donald Luskin, chief investment officer at the financial firm TrendMacro.