Answer: Mutual Funds
Explanation: Stock and bonds are direct instruments in specific securities. When you buy a bond, you directly buy the security and the same is the case with stocks.
However in case of Mutual funds, you (the investor) buy the mutual fund which in turns buys the underlying security which can be either a stock or a bond. So, mutual funds pool money and buy the security. So, you are an indirect holder in case of mutual funds and hence have a higher cost than others