The Howey Case
This particular Supreme Court case established just what a security was.
It started when a guy began selling real estate that his established orange grove just happened to be planted in. It was kinda implied that people got profit from these oranges. However, the dude's company managed all of the trees itself, and, if buyers didn't use the company's management services, the buyers couldn't realistically make any money off of their investment.
As a result, the court ruled that the acreage investment was a kind of security contract, and as such, came under different (higher) scrutiny than if the buyer had just bought non-productive-land.
Talk about makin' lemonade out of… oranges.