What Investing Your Cash Back in the S&P 500 Would Be Worth

By Bryce Casson, Founder · Cardocrat · Updated July 2026

The short answer: Here is a boring habit that quietly builds real money: instead of spending your cash back, invest it. If you had earned 2% back on your everyday spending and put every dollar of it into an S&P 500 index fund, about $6,600 of cash back from 2016 to 2026 would be worth roughly $14,000 today, a little over double what you put in. And that is the small version. Keep the same habit going for 30 years at the market’s long-run average and it grows to somewhere near $99,000, all from rewards you were going to earn anyway. Think of this as the calmer, more reliable cousin of our crypto rewards study.

The setup: 2% back, invested instead of spent

Let me keep the setup the same as our other studies so the numbers line up. Say you run about $2,500 a month, so $30,000 a year, through a card for normal everyday spending. A plain 2% flat-rate card like the Wells Fargo Active Cash or the Citi Double Cash pays you $600 a year in cash back. Most people let that money trickle back as a statement credit and never really notice it, which is fine, but it also means it quietly disappears back into everyday spending. This study asks a different question: what if you took that same $600 a year and put it into a low-cost S&P 500 index fund instead of spending it?

The 10-year backtest

So here is the exercise. Every year, your $600 in cash back buys into the S&P 500 at roughly that year’s level, and you leave it alone, so I value it at where the index sits today, around 7,540 as I write this in July 2026. The index climbed from about 2,090 in 2016 to that level over the decade, with a couple of down years along the way.

Year	Approx. S&P 500 level	$600 invested, worth today
2016	~2,090	$2,165
2017	~2,450	$1,850
2018	~2,745	$1,650
2019	~2,910	$1,555
2020	~3,220	$1,405
2021	~4,270	$1,060
2022	~4,100	$1,105
2023	~4,285	$1,055
2024	~5,430	$835
2025	~6,300	$720
2026 (YTD)	~7,200	$630
Total		~$14,000

Add it up and the same $6,600 of cash back, invested, comes to roughly $14,000 today. That is a little over double, and every dollar of it came from rewards you earned on spending you were doing anyway. The levels above are approximate yearly averages and this counts price growth only, so with dividends reinvested you would have a bit more.

Why this is steadier than the crypto version

If you read our crypto rewards study, this is the calm counterpart. That one produced a wild headline number, but almost all of it came from a single early year and a coin that can drop by half without warning. The S&P 500 is different. It is hundreds of the largest companies in the country, so the result here is not riding on one lucky year, it is spread across the whole decade. It had real down years, 2018 and 2022 both finished lower, and it recovered from both, the way it has recovered from every drop so far. You do not have to believe in any single stock or time anything. You just own the market and let it work.

The real money is in the time, not the decade

I want to be honest about one thing: the 2016 to 2026 stretch was a strong run for the market, closer to 13 to 15% a year than the long-run average. Do not plan on that repeating. The number worth building around is the S&P 500’s long-run return of about 10% a year. Here is why the habit still matters even at that calmer pace: $600 a year invested for 30 years at 10% grows to somewhere near $99,000. That is from a plain 2% card. If you earn 3 to 5% back with category cards, or you spend more than $30,000 a year, the ending number climbs from there. The power is not the rate on the card, it is doing this steadily for decades.

How to actually do it

None of this works if the cash back keeps vanishing into your statement, so the trick is to make investing it automatic. Pick a strong flat-rate card like the Active Cash or Double Cash, or lean on category cards where you spend the most, and redeem your rewards as actual cash rather than gift cards or trinkets. Then move that cash into a low-cost S&P 500 index fund or ETF on a set schedule, monthly or quarterly, so you never have to think about it. And pay the card in full every month, because one month of interest at today’s rates wipes out a year of 2% rewards. Run your own spending through the rewards calculator to see how much cash back you would really earn, then point it at the market and leave it alone.

Frequently asked questions

Is investing credit card cash back actually worth it?

Over time, yes. About $600 a year of 2% cash back, invested in an S&P 500 index fund, grew to roughly $14,000 over the past decade, and it builds toward around $99,000 over 30 years at the market’s long-run average. Any single year is small, but it compounds into real money.

How do I invest my cash back?

Redeem it as cash, either a statement credit you then transfer or a direct deposit, and move it into a low-cost S&P 500 index fund or ETF, ideally on an automatic monthly or quarterly schedule. Some cards and brokerages let you route rewards straight into a brokerage account so it happens on its own.

Is the S&P 500 safer than crypto for rewards?

It is far steadier. The S&P 500 is hundreds of companies rather than one coin, so it swings much less and has recovered from every downturn so far. It still has losing years, 2018 and 2022 both finished down, so it is not risk-free, but it is nothing like the leveraged bet a single cryptocurrency is.

What return should I expect?

The 2016 to 2026 decade ran hot at roughly 13 to 15% a year, which is above normal. The long-run S&P 500 average is closer to 10%. Plan with 10% and treat anything above it as a bonus.

What if my card earns more than 2% back?

Even better. Category cards that earn 3 to 5% on groceries, dining, or gas put more cash back into the fund every year, so the ending balance scales up with both your rewards rate and how much you spend.