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 30 Jul 2026

Monitored notional

$4,976 avg 7.93% yield

Monitored notional

€283,111 avg 2.66% yield

Amount EUR

€

Tenor 12m

2m4m5m8m11m14m17m20m23m34m

Strike width pts

Wider = fewer contracts. Auto fits your amount.

From the end-of-day EUR curve.

Implied rate · 12m EUR

2.66%

After tax: 1.96%

Cash today Target €100,000 · 0.20%: €100,197
Implied cost (12m): €2,803
Settlement at expiry: €103,000
After-tax settlement: €102,261

In plain terms You receive €100,197 today and repay €103,000 on 20 Aug 2027 — a total cost of €2,803.

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

A · Property

Box vs. realize vs. all cash

10-year wealth comparison for the down-payment.

Open →

B · Portfolio leverage

Box-leveraged vs. unleveraged

Leverage pays the moment portfolio return beats the box rate.

Open →

C · Decumulation

Living off the portfolio — sell or box?

Sell shares or roll a box line? Compounded across decades.

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D · Bridge

Closing the flat-to-flat gap

A short box line vs. the bank's 7% bridge loan.

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Real box prints

SPX · ESTX50

Executed (UTC)	Index	Expiry	Strikes	Contracts	Notional	Implied rate
30 Jul 22:02:07	SPX	18 Sep 2026	7000/8000	1	$99,415	4.38%
30 Jul 21:53:39	SPX	18 Sep 2026	7000/8000	1	$99,425	4.30%
30 Jul 21:13:50	SPX	18 Dec 2026	6000/7000	5	$491,500	4.54%
30 Jul 18:54:48	SPX	18 Sep 2026	6880/7880	1	$99,383	4.62%
30 Jul 18:21:10	SPX	16 Oct 2026	6000/7210	1	$119,880	4.45%
30 Jul 18:14:26	SPX	15 Jan 2027	6000/7000	200	$19,590,000	4.58%
30 Jul 17:18:35	ESTX50	18 Dec 2026	1000/6000	150	€7,426,050	2.60%
30 Jul 16:58:02	ESTX50	18 Sep 2026	1000/6000	400	€19,928,000	2.67%
30 Jul 15:01:57	ESTX50	20 Nov 2026	4200/7500	4	€131,024	2.43%
30 Jul 10:33:37	ESTX50	17 Dec 2027	5300/7300	1	€19,240	2.84%

Four-leg combo executions detected in the options trade tape. Clean boxes only; prior-session data.

What's a box spread?

Four options that combine into a fully-collateralised loan. The implied rate is what the market lends at against your portfolio.

Mechanics
Tax in DE
Risk + margin

Read the full guide →

Track your positions

$19 / €16 per month

or $129 / €110 per year · save ~43%

We watch the curve against your positions and flag only what changes a decision.

Roll alerts — before expiry, with the roll-into rate
Refinance alerts — when a longer tenor beats your locked rate
Rate history per tenor
Running cost across every box — pre- and after-tax
Broker auto-import or manual entry

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