Research
Box Spread Financing vs. Margin Loans
The 1-year Haven SPX Box Rate next to a published USD margin schedule.
Key takeaway
On October 6, 2026 the 1-year Haven SPX Box Rate was 4.88%. A USD margin schedule checked October 8 started at 5.38% on the first $100,000.
Current margin schedule
| Balance | Rate | Versus the October 6 Haven SPX Box Rate |
|---|---|---|
| 1-year Haven SPX Box Rate, October 6, 2026 | 4.88% | — |
| IBKR Pro USD, up to $100,000 | 5.38% | 0.50 pp higher |
| IBKR Pro USD, $100,000 to $1,000,000 | 4.88% | In line with 4.88% |
| IBKR Pro USD, $1,000,000 to $50,000,000 | 4.63% | 0.25 pp lower |
| IBKR Pro USD, $50,000,000 to $250,000,000 | 4.38% | 0.50 pp lower |
| $300,000 blended on the tiers above | 5.05% | 0.17 pp higher |
The line uses every year from 2012 through 2026. The cleaned history has a published 1-year rate in each of those years, including 2020. Interactive Brokers' USD Pro schedule is as shown on its margin-rate page on October 8, 2026. A $300,000 balance blends the first $100,000 at 5.38% with the next $200,000 at 4.88%, which is 5.05%. The page states a 0.75% minimum floor. Introduced clients may be charged a different rate. IBKR Lite was 6.38% at every listed tier. There is no public history of this schedule.
Haven SPX Box Rate history
The line below is only the 1-year Haven SPX Box Rate. It is not a historical margin rate. There is no public history of the margin schedule, so it is not drawn as a second line.
From 2012 through 2025 the 1-year Haven SPX Box Rate averaged 1.99% across 3,517 published days. That is the same history drawn above.
A margin debit is a loan from the broker, and the rate can change. The Haven SPX Box Rate is not that debit.
Sources: Methodology · published daily CSV · published JSON · Interactive Brokers margin rates. The table uses the cleaned daily history.
What this means
The schedule above is the comparison that can be made today: a posted margin schedule against one Haven SPX Box Rate print. No public history of that schedule exists, so the chart shows only the Haven SPX Box Rate. A margin debit is a broker loan that can change; the Haven SPX Box Rate is not that debit.
Haven Funding LLC is owned by Haven Systems LLC. Neither firm is a bank or a registered broker-dealer. Securities and execution services are provided through Interactive Brokers LLC. The Haven SPX Box Rate is a constant-maturity reference rate. It is not a Truth in Lending APR and not a commitment to lend.