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.

How are box spreads taxed?

It depends on where you pay tax. In Germany, Spain, France and the US the financing cost counts as a loss on the options that can reduce tax on other investment gains, but what it can offset, at what rate and in which year differs a lot. Our country guides on the Learn page explain each one.

Box spread rates today

Implied financing rates from S&P 500 and Euro Stoxx 50 box spreads, marked daily. As of 14 Oct 2026

Monitored boxes · SPX

$128,089 avg 4.87% yield

Monitored boxes · ESTX50

€327,266 avg 2.72% yield

Amount EUR

€

Tenor 12m

1m2m3m4m5m6m9m12m14m17m20m23m35m

Strike width pts

Wider = fewer contracts. Auto fits your amount.

From closing prices for EUR boxes, not from trades.

Implied rate · 12m EUR

3.07%

Cash today Target €100,000 · -2.98%: €97,021
Implied cost (12m): €2,979
Settlement at expiry: €100,000

In plain terms You receive €97,021 today and repay €100,000 on 15 Oct 2027 — a total cost of €2,979.

Last traded Nothing traded at these strikes. The last print on this expiry was 6000/6400 on 13 Oct 2026 at 2.420%. Different width, so the rate is comparable but the price is not.

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4-leg structure ESTX50 · EUREX

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

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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.

Open →

D · Bridge

Closing the flat-to-flat gap

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

Open →

Real box prints

All prints → Liquidity tracker →

Executed (UTC)	Index	Expiry	Strikes	Contracts	Notional	Implied rate
13 Oct 17:57:56	SPX	16 Oct 2026	7000/8000	1000	$99,953,000	5.89%
13 Oct 16:32:28	SPX	16 Oct 2026	7000/8000	2000	$199,906,000	5.89%
13 Oct 15:24:15	ESTX50	15 Dec 2028	1000/6000	3500	€163,345,000	3.22%
13 Oct 15:06:33	ESTX50	15 Dec 2028	1000/6000	500	€23,335,000	3.22%
13 Oct 14:33:55	ESTX50	18 Dec 2026	100/10000	1	€98,540	2.61%
13 Oct 14:21:45	SPX	16 Oct 2026	7000/8000	600	$59,985,600	2.96%
13 Oct 14:21:45	SPX	18 Dec 2026	7000/8000	600	$59,517,600	4.57%
13 Oct 14:21:45	SPX	16 Oct 2026	7000/8000	566	$56,586,416	2.96%
13 Oct 14:21:45	SPX	18 Dec 2026	7000/8000	566	$56,144,936	4.57%
13 Oct 13:18:22	ESTX50	17 Sep 2027	4800/6900	1	€20,370	3.33%
This month — volume · avg yield					€851,607,167 $3,916,783,306	2.77% 4.85%

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
Discount factor
Risk + margin

Read the full guide →

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