What Borrowing Against Your Portfolio Really Costs
We compare broker margin, bank loans secured by securities, and SPX box spreads: rates with sources and dates, calculations, and the risks of each approach. We are not a lender or a broker — the decisions are yours.
Annual Cost Difference
Per $100,000 borrowed
312bps
$3,123 / year
* Average of published rates: Robinhood, IBKR Pro, Charles Schwab, E*TRADE ($100,000), as of Oct 3, 2026. ZeroMargin Rate: ZMR, as of Oct 2, 2026.
Financing Cost Calculator
Enter your portfolio size and the amount you need. The calculator compares the annual cost of borrowing at the average broker margin rate and at ZMR.
Model Inputs
Capital Utilization Ratio
Percentage of your total portfolio buying power used as margin for this loan.
8.0%
Funding Source Comparison
Rates and terms of the main ways to borrow against assets. Each rate shows its source and date.
Research, Policy & Execution Notes
Structured analysis of financing markets, tax treatment, and governance controls for disciplined portfolio decisions.
How Synthetic Financing Can Change an Investment Strategy's Return Profile
A scenario analysis of how box financing and a collar can change the return profile of a stock position.
SPX vs SPY: Why Cheaper Financing Requires Active Management
A comparison of SPX and SPY structures for accessing portfolio liquidity without selling long-term holdings.
How to Think About Borrowing Against a Portfolio Without Selling
How to evaluate collateral, drawdown cushion, rate structure, tax timing, and forced-sale risk before borrowing against securities.
What CPI Means for Your Cost of Liquidity
Why CPI surprises can change the funding curve behind broker margin, SBLOCs, and box-spread liquidity.
US Liquidity Monitor
Market context for funding cost, risk regime, and spread behavior.
| Metric | Current | 7D Change |
|---|---|---|
SOFR | 3.89% | -1 bp |
UST 3M | 4.21% | -4 bps |
UST 10Y | 5.27% | +1 bp |
EFFR | 3.88% | 0 bps |
VIX | 15.52 | -0.55 pts |
SPX Box Spread | 4.85% | — |
How to read this snapshot
- SOFR and UST changes directly shift the reference floor for box spread implied rates. A declining SOFR typically compresses funding cost.
- The spread between the box rate and SOFR shows how much the market charges for box financing above the overnight secured rate; compare only at the same term and the same rate convention.
- When VIX rises, option spreads usually widen and building a box can cost more. A higher VIX on its own does not mean a higher risk of early exercise.