Stake
Stake is an exchange for the US stock market available on web and mobile devices. Funds can be deposited directly from a bank account and are automatically exchanged into US dollars. There is a $2 transaction fee for deposits as well as the option to speed up the transfer for another $2. There is a premium version with a monthly subscription that allows for immediate release of funds after selling a stock otherwise there is a 2 day holding period.
To find out more about this stock exchange you can visit their website here.