Part one was about the Fed and the end of QT. The takeaway there: the real tension doesn't sit with the central bank but with the US Treasury. This post looks at the how — at perhaps the most important and least understood lever in US debt policy: the tilt toward the short end.
What "bill-heavy" actually means
The Treasury funds itself with two kinds of paper. T-bills are short instruments maturing in up to one year, with no coupon, issued at a discount. Notes and bonds are coupon-bearing, maturing in two to thirty years.
The difference isn't technical, it's strategic. Issue long, and you lock in today's rates for years and pay a term premium on top — the extra compensation investors demand for holding long maturities. Issue short, and you save that premium, but you have to roll the paper over constantly.
The numbers, as of mid-2026
The T-bill share of outstanding US debt sits at roughly 21.9% — above the 15% to 20% range recommended by the Treasury's own advisory committee (TBAC).
One instrument shows the scale: in 2026 the 4-week bill is issued at an average of about $101 billion per offering, up from about $47 billion in 2016. It is now the single largest security the Treasury sells.
| Metric (as of) | Value |
|---|---|
| T-bill share of debt (mid-2026) | ~21.9% |
| TBAC recommendation | 15–20% |
| 4-week bill per offering (2026) | ~$101B |
| Same bill (2016) | ~$47B |
| FY2026 deficit | ~$1.9T |
| Gross maturities to refinance, FY2026 | ~$9.7T |
| Largest buyer group (Sep 30, 2025) | domestic investment funds |
Why the Treasury does it
It's a deliberate cost-risk trade-off, not an act of desperation. As long as long-term rates are high and carry a rising term premium, locking in for thirty years is simply expensive. The short end is cheaper and more flexible — and avoids cementing a high rate level for decades.
The price of this strategy comes later.
The mechanics of rollover risk
Bills mature fast and must be reissued constantly. That's exactly why fiscal year 2026 brings about $9.7 trillion of gross maturities to refinance. One important caveat: this is not new borrowing — by far the largest part is short-dated bills that mature several times within the year and get replaced. The figure looks enormous because the short end inflates it.
The real risk is in the detail: a growing share of the debt reprices frequently at whatever the current short-term rates are. The average maturity of the debt shortens. If the Fed holds rates high or hikes, that feeds through to refinancing cost quickly and broadly — not years from now, but at every rollover.
Who absorbs the flood of short paper?
The demand side is more concentrated than many assume. As of September 30, 2025, the largest buyers at auction were domestic investment funds — money-market funds, mutual funds, hedge funds — followed by broker-dealers, and only then foreign investors.
Two factors prop up that demand further. First, the Fed's overnight repo facility (ON RRP), where money-market funds had parked over $2 trillion at times, has drained to near zero — that cash flowed into T-bills. Second, the Fed itself has been buying T-bills again since December 2025 (through its reserve management purchases), soaking up part of the supply. A quiet symbiosis between debt management and monetary policy.
The limit — and the 2027 inflection
This strategy has a ceiling. With the bill share already above the recommended range, capacity for still more bills is thin. The likely consequence: from around 2027, coupon auctions (notes and bonds) will probably have to grow again. That shifts issuance to the long end — where investors demand a higher term premium, which tends to push long-term yields up.
To stabilize things, the Treasury also runs a buyback program that, by its own assessment, works well and supports market liquidity without materially changing the maturity profile.
A methodical bottom line
Measurable: The bill share is above the recommended range. The 4-week bill has roughly doubled since 2016. The average maturity is short. Domestic funds are the load-bearing buyer group. The Fed absorbs some too.
Interpretation: Whether the expected shift to larger coupon auctions from 2027 lifts long-term yields noticeably depends on inflation, deficits, and demand — that's a forecast, not a fact.
Bill-heavy funding isn't reckless in itself. It's a rational trade-off: cheaper today against more frequent repricing tomorrow. The risk isn't one dramatic moment but a concentration — a lot of debt repricing quickly, carried by a limited set of buyer groups. Not a crisis call. But the point to watch has a date on it: 2027.
This post is an analytical read, not investment advice. Study the Past — Improve your Future. 🥋