Acorns is a fairly new app that automatically invests your saved money into the market. It takes your loose or spare change from your bank account/debit card. Spare change from your bank account? How it works: say you spend $15.50 on an item, Acorns links to your bank and rounds the purchase to $16.00. It takes the fifty cents and invests it in the stock market. Acorns calls this a “round up.” Besides the round ups you can also make traditional deposits to the account.