Could you have a business in the U.S. which allows you to deposit money and make an investment in a share of stock and pick the outcome? Let me give an example.
I deposit money to the site and each dollar is represented as credits. Facebook stock is at $3/share. I decide to put up $3 for one share. I then choose if the stock will go up or down and the length of time. If I choose it goes up, and it indeed goes up, I win say 70% credits, and if it loses, I lost 85% of my credits toward that share. People could then cash out afterward.
So, would this be legal, or is it online gambling? I live in California. This system would be used online.