12 USC 1814 - Insured depository institutions

(a) Continuation of insurance 

(1) Banks 
Each bank, which is an insured depository institution on September 21, 1950, shall be and continue to be, without application or approval, an insured depository institution and shall be subject to the provisions of this chapter.
(2) Savings associations 
Each savings association the accounts of which were insured by the Federal Savings and Loan Insurance Corporation on the day before August 9, 1989, shall be, without application or approval, an insured depository institution.
(b) Continuation of insurance upon becoming a member bank 
In the case of an insured bank which is admitted to membership in the Federal Reserve System or an insured State bank which is converted into a national member bank, the bank shall continue as an insured bank.
(c) Continuation of insurance after conversion 
Subject to section 1815 (d) of this title and section 1464 (i)(5) of this title
(1) any State depository institution which results from the conversion of any insured Federal depository institution; and
(2) any Federal depository institution which results from the conversion of any insured State or Federal depository institution,

shall continue as an insured depository institution.

(d) Continuation of insurance after merger or consolidation 
Any State depository institution or any Federal depository institution which results from the merger or consolidation of insured depository institutions, or from the merger or consolidation of a noninsured depository institution with an insured depository institution, shall continue as an insured depository institution.