Box spread loan

This one is the road trip's financing question. Planning the multi-month trip - the road-trip car tool is its sibling - we wanted the car without handing a bank years of auto-loan interest, and it turned out you can borrow far cheaper by selling a box spread: four SPX option legs whose payoff is fixed the moment you open them, so the cash you collect today is really a loan against your portfolio, priced near the risk-free rate. We built this to see whether that actually beats the loan we would otherwise sign.

This calculator prices that trade like a loan officer would. Enter the amount, the expiry, and the implied financing rate, and it lays out the cash received, the repayment due, the effective APR after fees, and how it compares against the consumer loan you would have taken instead. It also covers the practical requirements - portfolio margin, European-style options, and Section 1256 tax treatment - so you can judge whether the strategy fits your account before trying it.