I dont remember if it was a series or a really long novel. It starts with a guy picking up a homeless girl and bringing her home. He sold a computer program that predicts the stock market for an insane amount of money and spoils the girl rotten. He gets a service/guard dog because of a break-in and takes the dog and the girl to NYC where they become friends with another couple who have two young daughters. The girl is running from her corrupt stepfather and the MC helps her create a fake id to protect her. I read the story a couple years ago and could never find it again. I can provide more details if needed.