NEW YORK (AP) — Stocks in the U.S. and Europe skidded Friday as investors worried about the financial stability of Turkey and how it might affect the global banking system.

Turkish President Recep Tayyip Erdogan has accumulated more and more control over the country's central bank as well as its financial system, which is now run by his son-in-law. Its currency is plunging and Turkey is also in a diplomatic spat with the U.S., a major trading partner.

Alex Dryden, global markets strategist for JPMorgan Asset Management, said Erdogan showed no signs of changing course Friday, and investors are...