The Home Owners Loan Act does not preempt a state law breach of contract claim that the bank (successor to a federal savings bank) miscalculated adjusted interest rates on loans by failing to apply the index it said it would or by confining the index to interest rates on certificates of deposit rather than all savings accounts.  Common law breach of contract claims impose no requirements other than those the bank voluntarily assumed in its agreements.  However, HOLA did preempt the claim that the bank chose the wrong substitute index when the index initially specified in the promissory note ceased to exist. The bank sufficiently obtained its primary federal regulator’s approval of the new index.