S&P 500 vs T-bills
Since Jan 1934, $10,000 in the S&P 500 grew to $175,803,392 (11.1% a year) and $10,000 in Treasury bills to $235,822 (3.5% a year). Try your own amount and dates, or add more assets.
Real monthly data through Sep 2026, updated monthly. How we calculate$10,000 put into the S&P 500 in Jan 1996 is now worth
S&P 500 came out on top, 10.5× Treasury bills, which reached $20,323. Just keeping up with prices needed $21,696, and 1 of 2 did better.
Full results by asset
| Asset | Worth now | Per year | Total return | Worst drop |
|---|---|---|---|---|
| S&P 500 | $213,542 | 10.5% | 2,035% | −49% (Mar 2009) |
| T-bills | $20,323 | 2.3% | 103% | none |
The chart uses a log scale: equal steps up mean equal percentage gains. What each line measures: S&P 500, S&P 500 monthly average level with dividends reinvested (an index fund, before its small fee); T-bills, interest on 3-month US Treasury bills, a stand-in for cash in a money market fund. Inflation uses the US Consumer Price Index. Monthly averages, data through Sep 2026; no fees or taxes. Past returns do not predict future returns.
Which has done better?
Over the whole period both have data, since Jan 1934, the S&P 500 came out ahead with 11.1% a year against 3.5%. Over the last 10 years the lead went to the S&P 500. Starting dates matter: across all 993 10-year stretches in the data, the S&P 500 beat Treasury bills 88% of the time.
| Period | S&P 500 | T-bills |
|---|---|---|
| Last year | 17.6% | 3.7% |
| Last 5 years | 13.0% | 3.8% |
| Last 10 years | 15.3% | 2.4% |
| Last 20 years | 11.2% | 1.6% |
| Last 30 years | 10.3% | 2.3% |
| Since 1934 | 11.1% | 3.5% |
Yearly return, to Sep 2026. The higher one in each row is green.
Investing a little every month
$100 a month from Sep 2016 to Sep 2026 is 121 buys and $12,100 in total. In the S&P 500 it would now be worth $27,585; in Treasury bills, $14,180. Monthly buying spreads the entry price, which matters most for the more volatile of the two.
Which is riskier?
The deepest fall from a high was 49% for the S&P 500, around Mar 2009, and 0% for Treasury bills, around Jan 1934. The S&P 500 asked more patience of its owners. These use monthly averages, so the worst single days were a little deeper.
What the numbers measure
- S&P 500: S&P 500 monthly average level with dividends reinvested (an index fund, before its small fee).
- T-bills: interest on 3-month US Treasury bills, a stand-in for cash in a money market fund.
No fees or taxes are included. Past returns do not predict future returns.
Common questions
The S&P 500 or T-bills: which has been the better investment?
Since Jan 1934, the S&P 500 has returned more: 11.1% a year against 3.5% for Treasury bills. Over the last 10 years, the S&P 500 came out ahead. Across every 10-year stretch in the data, the S&P 500 beat Treasury bills 88% of the time, so the answer depends heavily on when you start.
Which is riskier, the S&P 500 or Treasury bills?
By the deepest fall from a high, the S&P 500: the S&P 500 dropped as much as 49% (around Mar 2009) and Treasury bills as much as 0% (around Jan 1934), using monthly averages.
How much would $10,000 in the S&P 500 be worth today?
$10,000 put into the S&P 500 in Jan 1934 would be worth about $175,803,392 by Sep 2026. The same money in Treasury bills would be about $235,822. Change the amount and dates in the calculator to see any period.
What if I invested monthly in the S&P 500 or Treasury bills?
$100 a month from Sep 2016 to Sep 2026 adds up to $12,100. In the S&P 500 it would now be about $27,585; in Treasury bills, about $14,180.
FatDCA comparisons are educational estimates, not investment, tax or legal advice.
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