The U.S. has more than 4,500 banks — more banks than any other country. That huge number of lenders has shaped the economy in countless ways, but it also can pose risks.

Trading of First Republic Bank shares were halted multiple times today, as investors sold off shares, alarmed by financial disclosures from the bank.

Regulators need to decide how to recover the cost of rescuing Silicon Valley Bank and Signature Bank — and community banks across the country are warning they should not be on the hook.

Shares in the midsized lender continued to tumble as fears grow about First Republic's financial health grow even after it received a $30 billion lifeline from its bigger rivals last week.

The 40 branches of Signature Bank will become Flagstar Bank, starting Monday. Flagstar is one of New York Community Bank's subsidiaries.

The lenders including J.P.Morgan and Wells Fargo would deposit $30 billion into the beleaguered midsized lender as part of the rescue.

A drop in shares of European lender Credit Suisse sparked fears that banking turmoil is spreading around the world.

Some say the decision to guarantee deposits beyond the typical $250,000 limit was necessary to keep the financial system stable. Others argue this sets a bad precedent if other banks run into trouble.

Bank runs, by their very nature, happen fast. But in an age of instant communication, social media and money transfers at the touch of a button, they can now happen in the blink of an eye.

The declines come despite emergency measures by regulators to protect depositors at Silicon Valley Bank and Signature Bank and President Biden's remarks to reassure Americans.