CDs typically require a minimum deposit, and may offer higher rates for larger deposits. The best rates are generally offered on "Jumbo CDs" with minimum deposits of $100,000. Jumbo CDs are commonly bought by large institutional investors, such as banks and pension funds, that are interested in low-risk and stable investment options. Jumbo CDs are also known as negotiable certificates of deposits and come in bearer form. These work like conventional certificate of deposits that lock in the principal amount for a set timeframe and are payable upon maturity.