What is a swap, really?

A swap is the plainest idea in derivatives, buried under the most intimidating name. Two parties agree to exchange one stream of cashflows for another, on a schedule, for a fixed period. Nothing is bought. No asset moves. Only the difference between two payment streams changes hands.

That's it. Everything else — interest rate swaps, currency swaps, total return swaps — is the same skeleton with different cashflows hung on it.

The four things every swap specifies

• The two legs. What each side pays. One leg might be a fixed percentage; the other might float with a market rate, or track a stock's total return, or be denominated in another currency.
• The notional. The number both legs are calculated on. In most swaps this amount is never paid by anyone — it's a ruler, not a payment.
• The schedule. How often the legs settle: quarterly, semi-annually, annually.
• The tenor. How long the agreement runs — two years, five, thirty.

The notional is a ruler, not a payment

This is the single idea that unlocks the whole family. Take a $10,000,000 notional swap where one side pays 4% fixed and the other pays a floating rate that happens to set at 3% for the year:

• Fixed leg: $10,000,000 × 4% = $400,000
• Floating leg: $10,000,000 × 3% = $300,000
• Net settled: $100,000 flows from the fixed payer to the floating payer.

Ten million dollars of interest-rate exposure produced one hundred thousand dollars of actual cash movement. Nobody sent anybody ten million dollars. That ratio — large exposure, small cashflow — is why swaps are efficient, and it is also the first place leverage hides in this course.

The family, in one glance

• Interest rate swap — fixed cashflows for floating ones. By far the largest market.
• Currency and cross-currency swaps — cashflows in one currency for cashflows in another.
• Total return swap — the entire economic return of an asset (price moves plus dividends) for a financing cost. Unit 2 spends a whole lesson on why this one matters.
• Commodity swaps — a floating commodity price for a fixed one, used by producers and heavy users.

Where the risk actually lives

A swap is a promise, not a property right. If the other side fails halfway through a ten-year agreement, you don't own anything you can sell — you own a broken contract. That single fact drives everything in this course's second unit: collateral, margin calls, central clearing, and what happens when a counterparty can no longer pay.

Swaps are contracts used by companies, banks, funds and governments. Describing how they work is not a suggestion that anyone should enter one — most people reading this never will, and won't need to. The point is literacy — these contracts move trillions of dollars of exposure daily, and understanding them changes how you read financial news.

Try it now

1. An overnight benchmark over three years is below: SOFR, the dollar rate published every business day, read on the first business day of 2024, 2025 and 2026, then on the latest day. Note its range across those four readings.

2. Take the highest and lowest values you found. On a $10,000,000 notional, compute the annual cash difference between those two rates. That number is what one side of a swap was trying to make predictable.
3. Write down one obligation in your own life that is fixed (a fixed-rate loan, a fixed salary) and one that floats (a variable-rate loan, a savings rate). You've just identified which leg of a swap you naturally hold — an observation, not a plan to trade one.