What is a box spread?

A box spread is a combination of four European-style options (two calls, two puts) on the same index that together form a synthetic, fully-collateralised loan. The implied rate is what the market is willing to lend at against your portfolio.

How is the box-spread yield curve computed?

We derive the implied rate from daily settlement prices across all liquid SPX and Euro Stoxx 50 box-spread tenors. The curve refreshes after market close and shows market-implied financing rates from 1 to 36 months.

Which brokers support box spreads?

Tier 1: Interactive Brokers, Schwab (thinkorswim), Fidelity, E*TRADE, tastytrade, TradeStation, Tradier. Tier 2: Webull, Moomoo, Public. For ESTX50 in Europe, Interactive Brokers, Saxo, and Lynx are the common venues.

What about the €20,000 cap on derivative losses?

It's gone. The Jahressteuergesetz 2024 retroactively struck §20 Abs. 6 Satz 5 EStG — the rule that had capped Termingeschäft loss offsets at €20,000/year inside a segregated bucket. Box-spread carry now offsets your general Kapitalerträge — dividends, interest, ETF distributions, fund capital gains — at the 26.375% Abgeltungsteuer rate, with no cap. Direct single-stock losses still sit in their own bucket; that part of §20 Abs. 6 is unchanged.

Box-spread yield curve

Implied financing rates from S&P 500 and Euro Stoxx 50 box spreads, marked daily. As of 22 Jun 2026

Monitored Notional at Yieldbard

$4,976 avg 7.93% yield

Monitored Notional at Yieldbard

€258,387 avg 2.65% yield

Amount EUR

€

Tenor 12m

1m2m3m4m5m6m9m12m15m18m21m24m30m36m

Strike width pts

Wider = a larger gap between the two strikes and fewer contracts. "Auto" fits the width to your amount.

Rate interpolated from the latest end-of-day EUR box-spread curve. Reload to refresh after market close.

Implied rate · 12m EUR

2.54%

After tax: 1.87%

Cash today Target €100,000 · 0.29%: €100,289
Implied cost (12m): €2,711
Settlement at expiry: €103,000
After-tax settlement: €102,285

In plain terms You receive €100,289 today and repay €103,000 on 16 Jul 2027 — a total cost of €2,711.

4-leg structure ESTX50 · EUREX

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Action	Right	Strike	Qty
BUY	CALL	••••	••
SELL	CALL	••••	••
BUY	PUT	••••	••
SELL	PUT	••••	••

Strikes, contract count, and IBKR/CapTrader-ready combo limit unlock with a free account.

Use cases

Four calculators for real decisions — daily box rate, full German tax logic.

A · Property

Box vs. realize vs. all cash

10-year wealth comparison for the down-payment in Berlin, Munich, Hamburg.

Open →

B · Portfolio leverage

Box-leveraged vs. unleveraged

Buy more ETF than cash alone allows via a box spread — leverage pays the moment portfolio return beats the box rate.

Open →

C · Decumulation

Living off the portfolio — sell or box?

Funding annual spend: sell shares or roll a box line? Compounding effects across decades.

Open →

D · Bridge

Closing the flat-to-flat gap

Short box line vs. 7 % bank Vorfinanzierung — five-figure savings on a typical bridge.

Open →

What's a box spread?

Four European-style options that combine into a synthetic, fully-collateralised loan. The implied rate is what the market is willing to lend at against your portfolio.

Mechanics — how the four legs settle
Tax in DE — §20 EStG offset, simply
Risk + margin — what to watch for

Read the full guide →

Track your positions

$19 / €16 per month

or $129 / €110 per year · save ~43%

Box spreads are market-neutral — the curve around them isn't. We watch it against your positions and surface only what changes a decision.

Roll alerts — before expiry, with the rate you'd roll into
Refinance opportunities — when a longer tenor undercuts your locked rate
Historical rate per tenor — see how every tenor has traded over time, not just today
Lending cost tracker — running cost across every box, pre- and after-tax
Connect your broker or enter manually — auto-import from supported brokers, or type it in

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