Treasury bills: meaning and how T-bills work

What is a treasury bill?

A treasury bill (T-bill) is a short-term debt security that a government sells below its face value and repays at full face value on maturity. The gap between the two is the investor's return.

In Pakistan these are called Market Treasury Bills (MTBs). The State Bank of Pakistan sells them at auctions on behalf of the federal government. Tenors are measured in months, not years.

Formal definition and edge cases

• Zero-coupon. A T-bill pays no periodic interest, unlike a coupon bond. See coupon (bond). All the return comes from the discount to face value.
• Discount yield vs. money-market yield. Some markets quote the discount as a share of face value. Others quote it as a share of the purchase price. Both are then scaled to a yearly basis. The two figures differ, so check which convention a report uses.
• Short duration. Because maturity is short, a T-bill's price moves less with interest rates than a long bond's does. It still moves. See bond duration.
• Credit risk. A T-bill carries the credit risk of the issuing government. It is usually treated as the lowest-risk asset in its own currency, but sovereign default is possible.
• Shariah view. T-bills are interest-based. Government Ijara Sukuk are the usual Shariah-compliant alternative. See Islamic finance.

Worked example (hypothetical)

Take a bill with face value F. You buy it at auction for price P, which is lower than F.

1. On maturity the government pays you F.
2. Your gain is F − P.
3. The holding-period return is (F − P) ÷ P.
4. To compare bills of different tenors, annualise that return by scaling it to a full year. See annualized return.

The more the auction pushes P below F, the higher the yield. A higher price at auction means a lower yield.

T-bill yield and the SBP policy rate

T-bill yields in Pakistan usually move close to the SBP policy rate. Banks compare what a bill pays with what they can earn or pay at the central bank. The latest decision on record here is SBP policy rate raised by 50 bps to 12% with effect from 27.10.2026 (MPC).

Before such decisions, auction yields often move as banks price in an expected change. Rate moves are often described in basis points.

Where you see the term

• News: headlines report auction results as "cut-off yields" and the amount the government accepted against its target. See bond auction.
• Fiscal reporting: T-bills are a main tool for financing the fiscal deficit. They also feed into debt-to-GDP figures.
• Market analysis: analysts use T-bill yields as the "risk-free rate" in valuation. Money tends to move into T-bills during a flight to quality.
• Trading platforms: US T-bill yields show up in macro news feeds and fundamental analysis. Changes in yield gaps between countries can affect currency pairs.

Analysis is not a forecast. Leveraged forex and CFD trading on those moves can lose money fast.

Related terms

• Basis point
• Bond auction
• Face value (par value)
• Credit spread
• Accrued interest
• Saving, investing, loans
• Trading glossary

Frequent questions

What does treasury bills mean in simple words?

It is a short-term loan to the government. You pay less than the face value now and receive the full face value at maturity.

Do T-bills pay interest?

They pay no coupon. The return is the difference between the purchase price and the face value.

How are T-bills in Pakistan sold?

The SBP holds auctions for the government. Banks and other primary dealers bid, and individuals usually take part through a bank or a fund.

Why do T-bill yields follow the SBP policy rate?

Banks weigh bill yields against the rates available at the central bank. When the policy rate changes, auction yields tend to adjust.

Is a T-bill risk-free?

It is low-risk in local-currency terms, not risk-free. Its price changes with interest rates before maturity, and inflation can reduce its real return.