Money markets and rates — course checkpoint

You began this course with a policy rate on a headline. You finish able to describe the machinery that turns that headline into an actual price, and to read the gauges that show when the machinery is straining. Let us assemble it.

The four units, in one breath

The overnight rate. Banks settle in central bank reserves, and the total quantity of reserves is set by the central bank's balance sheet, not by banks. The overnight rate is the price of those reserves for one night — the anchor from which every longer rate is built. Central banks enforce their target through a corridor (a lending facility as ceiling, a deposit facility as floor, reserves kept scarce) or a floor system (reserves abundant, the rate pinned near what the central bank pays on them). Open market operations move the quantity; since 2008 they mostly operate as standing facilities rather than daily fine-tuning.

Repo. A sale with an agreed repurchase — economically a secured loan, legally a transfer of title, and that legal form is why repo funds so cheaply. The haircut is the cushion: cash = collateral × (1 − haircut), and read backwards it is leverage, 1 ÷ haircut. A repo rate spikes when cash is scarce; a single issue goes special — its repo rate falling below general collateral — when the bond is scarce. Opposite directions, opposite causes. September 2019 showed both that reserves can become scarce without anyone deciding they should, and that the demand curve for reserves has a wall nobody can locate in advance.

Reference rates. A fixing determines cash flows for people who never traded at it, which is why one basis point is worth real money and why LIBOR's design was untenable. LIBOR failed twice over: misconduct, and — decisively — the disappearance of the unsecured term interbank market beneath it. SOFR replaced it in dollars, secured, transaction-based, enormous; €STR did the equivalent in euros with an unsecured design, because that is where the euro area's data was deepest. The cost of the change is honest: overnight rates must be compounded in arrears, and a secured benchmark carries no credit signal, which leaves banks with genuine basis risk.

Short-term instruments. Bills are quoted on a discount basis, (F − P)/F × 360/t, but compared on a coupon-equivalent basis, (F − P)/P × 365/t for bills of 182 days or less — about 13 basis points apart on a 91-day bill priced at 98.75. Past 182 days that simple form stops being the published investment rate, because Treasury switches to a semi-annual formula of its own. Commercial paper is a discounted corporate liability whose real risk is rollover, not default. CDs are interest-bearing bank liabilities. Money market funds package all of it, and "breaking the buck" is what happens when a portfolio that people treated as cash proves not to be.

The two habits worth keeping

1. Ask whether it is a cash problem or a collateral problem. Almost every confusing headline in this market resolves the moment you decide which of the two you are looking at. Cash scarcity pushes repo rates up; collateral scarcity pushes a specific issue's rate down. The same word — "squeeze" — is used for both.

2. Watch the spreads, not the levels. The level of the overnight rate is policy. The spreads around it — secured against unsecured, market rate against the target range, one general collateral rate against another — are where the plumbing speaks. Money markets are the shortest-dated, fastest-rolling claims in the system, so a loss of confidence appears here first, as a refusal to roll rather than a slow drift in price.

And what this course does not give you

It does not tell you what any central bank will do. It does not tell you what a widening spread implies about tomorrow. Funding spreads are gauges to read, not signals to act on, and the September 2019 episode is a case study of a documented past, not a template for a predicted future. Everything here has been education about how a market works — never advice about what to do in it, and nothing in this course is a recommendation to buy, sell, or position for anything.

Before you sit it

Each of these is a minute at your desk. Any one that is not names the lesson to reopen first.

• Say how a central bank makes the market rate sit where it wants it — How does a central bank actually enforce its target rate?
• Describe a repo as a loan, naming what secures it and who holds it — What is a repo, and why does the whole system run on it?
• Say what SOFR is measured from, and what LIBOR was measured from — How do SOFR and €STR actually work?
• Say how a Treasury bill pays you when it carries no coupon — How is a T-bill priced if it never pays a coupon?

Try it now

1. Your one-page dashboard for a single recent date, 24 September 2026, is the four tables below: the policy rates; the dollar reference rates, for SOFR and EFFR; the funding spreads, for EFFR minus SOFR and SOFR minus the bottom of the Fed's range; and the 4-week and 13-week bills' coupon-equivalent yields. Each table carries more rows than the dashboard needs; pick out the ones named here.

2. Write five sentences about that date — one per unit theme, plus one on what you cannot tell from these numbers alone.
3. Keep the dashboard. Behind you in this domain sit bonds, duration and credit, and ahead of you short selling and lending — and every one of those prices is discounted back to the overnight rate you have just spent a course learning to read.

Checkpoint quiz next. Nothing in this course was a recommendation, a forecast, or a view on policy — you have learned to read the plumbing, which is a skill, not a signal.