Final answer:
Regulation D limits the number of certain types of withdrawals from savings and money market savings accounts as part of banking regulations aimed at maintaining solvency and protecting depositors' interests.
Step-by-step explanation:
The regulation that limits the number of certain types of withdrawals from savings and money market savings accounts is known as Regulation D. It falls under the category of bank regulation, which encompasses various rules including reserve requirements, capital requirements, and restrictions on investments, intended to maintain banks' solvency by avoiding excessive risk. Savings accounts are a component of what is known as M2 in the money supply, which has become similar to M1 (that includes checking accounts) due to advancements in banking technology that facilitate access to savings accounts. Financial protection for depositors is further provided by government agencies such as the FDIC for banks and the NCUA for credit unions, which insure savings accounts up to certain limits.