Why mutual funds are known as the "ultimate couch potato investment?" Here's my own idea about it.
Since mutual funds are collection of investment money pooled from a lot of people where the fund manager and his/her team assistants will invest to the specific securites (stock, bonds, or money market funds) it would be most likely to be the "ultimate couch potato investment" generally because, you just have to invest and this investment program will professionally managed, all you have to do is wait and see if your investment are going well or not.
That was only "my idea" how about yours?
Here's some related about mutual funds, the open-end and close-end funds.
If I would choose between open-end funds and close-end funds,,
I would rather choose open-end funds. Why would I? Basically because it can fund issues as many shares as an investor can, meaning it can attract more investor and able to hire leading managers -- with better management talent, it would help to lessen the risky part of mutual funds, since it was professional and well-known. Open-end funds can also reduce the expenses, the better the open-end funds the lower can be charge to annual operating expense and lastly it is fee-free selling where you don't have the cost and trouble of selling your shares to another investor.