When it comes to the stock market, it’s not always easy to know whether a stock that claims to be green is really green. That’s why the Luxembourg Stock Exchange has created the world’s first exchange that will trade nothing but green securities. It’s being called the Luxembourg Green Exchange, and it intends to act as a gatekeeper for green bonds and other environmentally-focused financial instrument to help reduce ambiguity in the market. The exchange will be a boost to the green market, which is expected to reach almost $72 billion a year, up from $48 billion in 2015.