Hidden Economics

Bank Economics

Understand how banks make money from money itself: a thin spread, amplified by leverage, into large returns and large risks.

  • Intermediate
  • 8 min total
  • 11 chapters

What decision this helps you make: How to see what a bank actually does, where its profit comes from, and where its danger lives.

What this topic is

A bank borrows money cheaply (mostly your deposits) and lends it out at a higher rate. The gap, called the net interest margin, is its core profit. Because it lends far more than its own capital (leverage), a thin spread on a huge base becomes a large return.

Why it matters

Banking is one of the most important and least understood businesses in the economy. Understanding the spread and the leverage explains how banks earn, why they're so profitable in good times, why they fail so catastrophically in bad times, and why they're so heavily regulated. The same leverage that magnifies profit magnifies risk.

Who should learn it

Anyone who wants to understand how banks really work, and anyone puzzled by how an institution can be hugely profitable one year and collapse the next.

What you will understand

  • See how a bank profits from the spread between borrowing and lending
  • Understand how leverage turns a thin margin into big returns
  • Know why the same leverage makes banks fragile
  • Recognize the two great bank risks: defaults and runs

Prerequisites

Common misconception

"Banks make money by keeping your deposits safe." Banks don't keep your deposits in a vault. They lend most of them out at a higher rate than they pay you, and pocket the difference. Your deposit is the bank's cheap raw material, lent out many times over. The bank is a spread-and-leverage machine, not a vault.