Think of a corporate bond sale or an IPO (when a company first sells shares to the public). These are really just high‑stakes auctions. Each investor has their own private guess about what the asset is truly worth. When you bid, your offer says something about what you know. The final price brings together many such pieces of scattered information. This chapter gives you a way to understand how different auction designs sort through private information, why winning can be terrible news, and when the seller should prefer one format over another.