Yes, absolutely. Public and private companies. And also some specific technologies.

Edit: let me give you a simple example. In late 2005 I proposed an investment to a wealthy relative: buy $100,000 of GOOG and $100,000 of BIDU. Any loss would be covered by me as debt, to be repaid over the next 10 years, with a stop-loss at -50% ($100,000). Any gain would be split half and half. Hold it for 10 years, then sell. Unfortunately my relative didn't accept. Baidu did 30x in 10 years. Google did ~6x.