When-Issued Trading and STRIPS

The U.S. Treasury market is the deepest, most liquid securities market on the planet — $27.9 trillion in marketable debt outstanding as of December 2024, with roughly $900 billion changing hands every day (SIFMA, 2024). Behind that liquidity sit two mechanisms most investors never think about but that shape how Treasuries are priced, issued, and restructured: when-issued trading and STRIPS.

When-issued (WI) trading lets the market discover a new security's price 5–7 business days before the auction even settles. STRIPS — Separate Trading of Registered Interest and Principal of Securities — let dealers and institutions break eligible Treasury notes and bonds into individual zero-coupon pieces that trade on their own. When the Treasury announced its November 2024 quarterly refunding at $125 billion across 3-year, 10-year, and 30-year maturities, WI trading began that same day, establishing expected yields before a single bond was formally issued. Meanwhile, roughly $340 billion in STRIPS sat outstanding (about 1.2% of marketable debt), quietly serving pension funds, insurers, and retirement savers who need precise cash flows at precise future dates (U.S. Treasury, MSPD December 2024).

What follows is a mechanical walkthrough of both processes — how they work, how to price a STRIPS component, the risks that come with duration and phantom income, and a practical checklist before you trade either one.

TL;DR: When-issued trading lets you buy or sell a Treasury security before it formally exists, establishing market-clearing yields ahead of auction day. STRIPS let you decompose a Treasury bond into individual zero-coupon cash flows — powerful for liability matching but carrying amplified interest-rate risk and a phantom-income tax problem you need to plan for.

What When-Issued Trading and STRIPS Actually Are (And Why They Exist)

When-issued trading is exactly what the name implies: trading a Treasury security after the auction is announced but before the security is actually issued and settled. WI trades don't settle on the trade date — they settle on the auction settlement date, which is typically T+1 after the auction itself (Treasury Market Practices Group best practices). If you buy a 10-year note on a when-issued basis five days before the auction, you're locking in a yield now but won't exchange cash and securities until after the auction clears.

That delay creates settlement risk. The TMPG imposes a fails charge on parties who don't deliver on time: max(0, 3% minus the federal funds rate), annualized. The charge exists to discourage strategic settlement failures (where a party might profit from not delivering in a low-rate environment).

STRIPS have a different purpose entirely. Launched by the U.S. Treasury in February 1985, the program lets eligible Treasury notes and bonds be separated into individual zero-coupon components — each semiannual coupon payment becomes its own security, and the final principal repayment becomes another. Before STRIPS existed, investment banks improvised their own versions: Merrill Lynch created TIGRs (Treasury Investment Growth Receipts), Salomon Brothers offered CATS (Certificates of Accrual on Treasury Securities), both held in trust accounts with the underlying Treasuries as collateral. STRIPS standardized the process and eliminated the credit risk of the intermediary.

Two types of components emerge from stripping:

Coupon strips (C-STRIPS): created from individual semiannual interest payments. Here's the critical detail — C-STRIPS are fungible across parent securities. A coupon strip maturing on May 15, 2035, is identical regardless of which bond it came from.
Principal strips (P-STRIPS): created from the corpus of the bond. Each P-STRIP carries a unique CUSIP tied to its parent security, making it non-fungible.

Eligible securities include notes and bonds with original maturities of 10 years or more, and the minimum par amount for stripping is just $100 (U.S. Treasury, TreasuryDirect). A 30-year bond separates into 61 components (60 semiannual coupons plus 1 principal payment). A 10-year note yields 21 components (20 coupons plus 1 principal). Every one of these components is held and transferred through the Federal Reserve's book-entry system (Fedwire Securities Service) — no paper certificates, no trust accounts, just electronic entries.

How WI Trading and Stripping Work in Practice

The When-Issued Cycle

The cycle follows a predictable pattern: Treasury announces the auction → WI trading begins the same day → auction occurs → settlement T+1 after auction.

Take the November 2024 quarterly refunding. The Treasury announced it would auction $42 billion in 10-year notes and $25 billion in 30-year bonds (among other maturities). When-issued trading opened immediately. Over the next several days, dealers, hedge funds, and institutional investors traded the not-yet-issued securities, establishing the market's best estimate of where the auction would clear. The 10-year note ultimately auctioned at a high yield of 4.347%; the 30-year bond at 4.542% (U.S. Treasury, November 2024 refunding).

Why this matters: WI trading isn't just a convenience — it's the primary mechanism for pre-auction price discovery. Participants compare the WI yield to the existing secondary market yield curve to judge whether the new issue is trading rich (expensive, lower yield than comparable existing securities) or cheap (higher yield). That assessment drives their auction bids.

The Stripping Process

Stripping is mechanically straightforward. A dealer or institutional investor instructs the Federal Reserve's book-entry system to separate an eligible bond into its individual coupon and principal components. Each component receives its own CUSIP and begins trading independently as a zero-coupon security. No approval process, no special authorization — if you hold an eligible bond in book-entry form, you can strip it.

Reconstitution is the reverse: reassemble all coupon strips (with matching payment dates) plus the principal strip into a whole bond. The Federal Reserve itself can reconstitute STRIPS in its System Open Market Account (SOMA) portfolio (Federal Reserve Bank of New York).

The Historical Arc

The program's reach has shifted over time. In 1997, the Treasury expanded STRIPS eligibility to all notes and bonds with 10-year-or-longer original maturities, broadening the universe of strippable securities significantly. STRIPS outstanding peaked at roughly $225 billion in 2000–2001, when total marketable debt was about $3.3 trillion — a 6.8% share, well above today's 1.2% (Treasury Bulletin historical tables). The decline in share reflects the massive growth of total Treasury issuance rather than a loss of interest in STRIPS.

When WI Trading Goes Wrong (The Salomon Brothers Scandal)

The most infamous when-issued episode came in August 1991, when Salomon Brothers submitted unauthorized bids exceeding 100% of a 2-year note auction, effectively cornering the when-issued market. The firm controlled approximately 94% of the issue (U.S. Treasury / SEC enforcement records). Short sellers who had sold the note on a WI basis found themselves unable to deliver — Salomon was the only source.

The fallout reshaped Treasury market regulation. Reforms included the 35% single-bidder limit (no single entity can win more than 35% of an auction) and changes to competitive bidding rules. The point is: when-issued trading carries real counterparty and market-structure risk, and the rules governing it exist because someone once exploited every gap.

Pricing a STRIPS Component (Worked Example)

Understanding how STRIPS are priced clarifies why they attract certain investors — and why they terrify others.

Your situation: You're considering the principal strip from a 30-year Treasury bond with $100,000 face value and 20 years remaining to maturity. The prevailing 20-year zero-coupon yield is 4.60%.

Step 1: Identify the cash flow. The principal strip pays $100,000 at maturity in 20 years. No interim payments. No coupons. One lump sum, two decades from now.

Step 2: Apply the present value formula. Treasury convention uses semiannual compounding:

PV = $100,000 ÷ (1 + 0.046/2)^(20 × 2) = $100,000 ÷ (1.023)^40

Step 3: Compute the discount factor. (1.023)^40 = 2.4866

Step 4: Calculate the price.

PV = $100,000 ÷ 2.4866 = $40,215.51

You pay roughly $40,216 today to receive $100,000 in 20 years. The $59,784 difference is your accumulated interest at a 4.60% yield — a 59.8% discount to par.

Step 5: The tax catch. Even though you receive zero cash until maturity, the IRS requires you to report annual "phantom income" — the accrued original issue discount (OID) — as ordinary income each year. You owe tax on money you haven't received yet. This is why STRIPS are overwhelmingly held in tax-advantaged accounts (IRAs, 401(k)s, pension funds).

The practical takeaway: that 59.8% discount makes STRIPS deeply appealing to investors with known future liabilities — a retirement date, a college tuition bill, an insurance obligation. You know exactly what you'll receive and exactly when. But the phantom-income problem means you need to pair the investment with the right account structure, or you'll face tax bills with no cash flow to pay them.

The Risks You Need to Measure (Not Just Acknowledge)

Duration Exposure (The Big One)

STRIPS carry far higher duration than coupon-bearing Treasuries of the same maturity. A coupon bond's duration is pulled shorter by the interim cash flows (each coupon payment is a mini-maturity). A zero-coupon bond has no such pull — its duration essentially equals its maturity.

A 30-year principal strip can have a modified duration near 29 years. The implication is stark: a 1 percentage point rise in yields causes roughly a 29% price decline. For your $40,216 principal strip, that's a loss of approximately $11,663 on paper from a single percentage point move. Duration is the price you pay for the certainty of that future cash flow.

The durable lesson: STRIPS are not "safe" just because they're backed by the U.S. Treasury. They are safe from default risk — but they carry enormous interest-rate risk if you sell before maturity.

Phantom Income Taxation (The Cash Flow Mismatch)

We covered the mechanics above, but the risk deserves its own emphasis. In a taxable account, you owe ordinary income tax on accrued OID every year. In the early years (when the accrued amount is small), this may feel manageable. As the bond approaches maturity and the accrual accelerates (compounding on a larger base), the annual tax bill grows — still with zero cash income to offset it. Hold STRIPS in tax-advantaged accounts unless you have a specific, deliberate reason not to.

Liquidity Risk (Wider Spreads, Thinner Markets)

STRIPS trade less frequently than whole Treasury securities. Bid-ask spreads on STRIPS run 2–5 basis points, compared to less than 1 basis point for on-the-run whole Treasuries (SIFMA). That spread differential matters if you need to sell before maturity. Use limit orders rather than market orders when trading STRIPS — the thinner liquidity means market orders can fill at unfavorable prices.

When-Issued Settlement Risk

WI trades settle only after the auction. If the auction yield comes in significantly different from the WI trading level, one counterparty faces a mark-to-market loss at settlement. You agreed to buy at a 4.30% yield, but the auction cleared at 4.50% — you're now paying above-market price. The TMPG's fails-charge mechanism helps, but it doesn't eliminate the fundamental risk that the world changes between your WI trade and settlement day.

Reconstitution Arbitrage Limits

In theory, if STRIPS components are collectively cheaper than the whole bond (or vice versa), a dealer can strip or reconstitute to capture the difference. In practice, this arbitrage is constrained by transaction costs, capital requirements, and the fungibility asymmetry — C-STRIPS are interchangeable across parent securities, but P-STRIPS are not. That asymmetry limits how quickly mispricings correct and means the spread between whole bonds and their STRIPS components can persist longer than pure theory suggests.

Before You Trade: A Practical Checklist

Check the auction calendar. Confirm the announcement date and WI trading start date using the Treasury auction calendar before placing any when-issued orders.
Compare WI yield to the curve. Is the new issue trading rich or cheap relative to existing secondary-market securities at similar maturities? If you can't answer this question, you aren't ready to trade WI.
Verify the CUSIP. For STRIPS, confirm whether you're buying a coupon strip or principal strip, and verify the remaining maturity. C-STRIPS and P-STRIPS with the same maturity date are not the same security.
Hold STRIPS in tax-advantaged accounts. Unless you have offsetting losses or a deliberate tax strategy, keep STRIPS in an IRA, 401(k), or similar account to avoid phantom-income taxation.
Stress-test your duration. Calculate the modified duration of any STRIPS position and apply a ±100 basis point yield shift. If the resulting mark-to-market loss exceeds what you can tolerate, reduce the position size.
Use limit orders for STRIPS. Bid-ask spreads of 2–5 basis points mean market orders can cost you. Set your price and wait.
Understand WI settlement conventions. WI trades settle on the auction settlement date (typically T+1 after auction day), not on your trade date. Plan your cash accordingly.
Assess counterparty credit for WI trades. Settlement is delayed, so you need your dealer or counterparty to remain creditworthy through to settlement day. This is not hypothetical — the Salomon Brothers episode showed what happens when market structure is exploited.