By definition, a small CD is any CD with less than $100,000 in it. Even if you have over $100,000 to invest, it is not always smart to put all of your money into a large CD. This is true even with the added interest rate that some banks will attach to large CDs. For example, assume that you have $250,000 to invest. You do have the option with this large amount of money to invest it all into a single large CD and see a great interest rate. But what happens if you need to gain access to your CD prior to the end of the CD contract? If you need to withdraw your money early, you will face a penalty fee imposed by the bank.
Rather than risking losing money due to early withdrawal penalties in a 60 month large CD, consider breaking the $250,000 into two or more groups. If you have two CDs at $125,000, you will still get the added interest rate, but you will be lowering your risk of an early withdrawal if you have one CD for 60 months and one for 12. This works because at the end of 12 months, you gain access to your money if you need it without succumbing to the early withdrawal. If you need money, you can then withdraw it and reinvest the money that you did not need within another CD. This can be done multiple times throughout your investing years, allowing you more freedom of access to your money.