The Biggest Mistake You Are Making On Your Mortgage
The Old Way
The traditional playbook for buying a house: get pre-approved, lock your rate, put 20% down, and get your mortgage. That plan was written for people who don’t own any assets. If you own a brokerage account with a portfolio, this playbook is a mistake that can cost you tens of thousands of dollars a year.
Almost everyone who buys a home while owning a portfolio makes a mistake in one of these two ways.
Mistake One: You Borrow From The Most Expensive Lender Available
As of mid September 2026, mortgage rates sit above 7% with little relief in sight. This rate is a function of many things, but most importantly it treats you as a simple combination of your credit score and collateral (the house you just bought). It doesn’t give you the benefit of the portfolio you own. As a result, you sign a 30-year contract at 7% while the same market that institutional borrowers use would finance your exact portfolio at 4.5%.
Mistake Two: You Sell The Portfolio To Pay Cash
This mistake might be worse than the first. You sell appreciated stock for a large down payment or to buy in all cash. You incur capital gains and sell a compounding asset in one fell swoop. You congratulate yourself for having no debt, while costing yourself an immediate tax bill, tax advantages on future financing, and compounded gains.
What Do Institutions Do?
Professional institutions do not sell their best assets to raise cash, nor do they use their least valuable assets to finance their activities. They find ways to leverage their best assets in order to get the cheapest and most favorable funding from the market.
The structure is called a Box Spread — four options that cancel market direction and leave a fixed cash flow. When the position is opened, cash comes in upfront. At a set future date, a known amount goes back out. The implied rate closely tracks benchmark treasury rates, which is roughly the rate at which the U.S. government itself can borrow.
Enter Alterra
Alterra is not a bank nor a brokerage. We are financial advisors who execute and manage box spreads so you can borrow against the portfolio you already have.
Your assets stay exactly where they are at your brokerage. We review your holdings and show you the exact amount and schedule at which the market will let you borrow (2-3% less than current mortgage rates). We execute the trade for you and you take the cash. It’s as simple as that.
If you already own a mortgage with a rate higher than what we can get you - we can also help you take out a box spread and pay off your more expensive mortgage. I’m happy to talk through whether box spreads make sense for your situation. Feel free to reach out to me either via email [email protected] or on LinkedIn.
