The jitters mounted a day earlier in California.

Shares in Silicon Valley Bank plunged 60% or more after it said it was trying to plug a hole in its balance sheet.

The news compounded concern over moves by crypto bank Silvergate to wind down.

Both firms had specific issues, but investors are also concerned it could be a sign of mounting trouble for the sector.

On Friday the the STOXX European banking index tumbled over 4%.

Some individual names did even worse.

Deutsche Bank fell as much as 8%.

Credit Suisse, also battered by its own troubles, sank to a record low.

The losses saw European stocks overall lose around 1.5% in morning trade.

Most analysts don't see a systemic threat to global banking for now.

But they say the negative effects of rising interest rates are being felt.

Among other factors, that's driven a slide in the value of government bonds, which make up a big slice of bank assets.

Now stubborn inflation could mean yet more rate hikes ahead.

The question for many is whether trouble at two U.S. banks is a local story - or the start of something bigger.