NEW YORK — Eleven of the biggest U.S. banks Thursday announced a $30 billion rescue package for First Republic Bank in an effort to prevent it from becoming the third to fail in less than a week and head off a broader banking crisis.

San Francisco-based First Republic serves a similar clientele as Silicon Valley Bank, which failed last week after depositors withdrew about $40 billion in a matter of hours. New York’s Signature Bank was shuttered Sunday. It appears First Republic, which had deposits totaling $176.4 billion as of Dec. 31, was facing similar issues.