Market Failure - Where Do You Think the Markets Have Failt?

Economists do believe in markets, but there's also such a thing known as market failure. I'm curious where you would say the markets have failed in the past 20 years. One place where i think markets have failed is in the labor marketi nomists are increasingly starting to understand the ways in which there is something we call monopsony power. The decrease of unions has probably not helped here.