Pay off a 3.5% mortgage, or invest the extra $500?
$500 a month, from January 2015 to June 2026. S&P 500: $161,626. Interest saved: $13,982.
$500 a month from January 2015 to June 2026, $69,000 in total. One line invests it in the S&P 500, the other saves 3.5% mortgage interest. Invest mode with a monthly plan, 9:16, rendered in the browser.
What it didThe average viewer watched 14 of its 16 seconds. 534 people saved it and 160 followed the account off it.
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Caption as posted
Could paying off a low-interest mortgage early cost you over $78,000?
$500/month for 11.5 years = 138 payments = $69,000 either invested or used to prepay the mortgage
📈 Invested in the S&P 500 $69,000 → $161,626 +$92,626 gain
🏠 Put toward a 3.5% mortgage $13,982 estimated interest saved
The difference:
$92,626 market gain − $13,982 interest saved = $78,644 more wealth in this historical model
Paying off debt gives you a certain return equal to the interest you avoid. The S&P 500 had a much stronger run over this period.
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📊 Sources: Historical S&P 500 returns and a 3.5% fixed-mortgage model (Jan 2015 to Jun 2026).
Made with chartrace.app.
⚠️ General information, not investment advice. Past performance is not a guide to future results.
The same $69,000 goes in either way. Paying down a 3.5% loan saves 3.5% and nothing more. The market promised nothing and paid $147,644 more.
| S&P 500 | Interest saved | |
|---|---|---|
| Ended at | $161,626 | $13,982 |
Questions
Is this an argument against paying off a mortgage?
No. Paying down a 3.5% loan is a guaranteed 3.5%. This chart shows what the same money did in the market over one particular eleven-year stretch, which happened to be a strong one.
What would change the answer?
A higher mortgage rate, a weaker market, or needing the money at a bad moment. Open the chart in the editor and change the rate or the window to see it.
Methodology
Figures are the ones the reel ends on, in June 2026. The market line is Yahoo Finance daily closes for the S&P 500 and excludes dividends. The interest line is modelled at 3.5% a year on the balance the extra payments retire. Taxes are not included, and a mortgage paid down is a certain return while the market one is not. Past performance is not a guide to future results. This page is general information, not investment advice.
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