Systemic risk is when something bad happens to a lot of companies or people all at the same time. It can happen when a company makes a bad choice that affects other companies, when natural disasters happen, or when banks have a lot of money come in and go out all at once. For example, the coronavirus pandemic is spreading around the world, and a lot of people and companies are losing money because they can't go out and do things the way they usually do. That's an example of systemic risk.