I am interested to buy some shares in the future. Can anybody tell me is there any kind of stock loan which doesn't need collateral?
In the U.S. it is typical that a stock brokerage account can be set up to buy stock with up to half the cost being borrowed from the broker. This is called a margin account. The stock purchased must remain in the account until sold (or the loan is paid off), as it serves as built-in collateral for the loan. If the market price for the stock goes down too much, you will be required to add money, or the stock will be sold to cover the loan. See this question for some more information.