What if you'd held TNDM?
A $1,000 investment in Tandem Diabetes Care, Inc. (TNDM) at the month-end close of 2013-11 would be worth $90.41 at the close of 2026-09 — -91.0% total return, dividends reinvested. The same $1,000 in the S&P 500, dividends reinvested, would be worth $5,349.
Your scenario
Result
If you'd bought $1,000 at the start of each year
Value of $1,000 invested on January 1 of each year, held to 2026-09, dividends included.
Every year, $1,000 from 2013
| Year | Value of $1,000 | Year return |
|---|---|---|
| 2013 | $1,000 | — |
| 2014 | $493 | -50.7% |
| 2015 | $458 | -7.0% |
| 2016 | $83.43 | -81.8% |
| 2017 | $9.16 | -89.0% |
| 2018 | $147 | +1508.9% |
| 2019 | $231 | +57.0% |
| 2020 | $371 | +60.5% |
| 2021 | $584 | +57.3% |
| 2022 | $174 | -70.1% |
| 2023 | $115 | -34.2% |
| 2024 | $140 | +21.8% |
| 2025 | $85.29 | -39.0% |
| 2026 | $77.22 | -9.5% |
Best and worst month-end to buy
The best single month-end close to have bought TNDM was 2017-12 ($2.36): $1,000 then is $8,432 today. The worst was 2014-01 ($259): $1,000 then is $76.98.
FAQ
What would $1,000 in TNDM be worth today?
A $1,000 investment in Tandem Diabetes Care, Inc. (TNDM) at the start of 2013 would be worth about $90.41 today, a total return of -91.0%. Dividends are reinvested in these figures.
What were the best and worst years for TNDM?
Tandem Diabetes Care, Inc. (TNDM)'s strongest calendar year since 2013 was 2018, a +1508.9% return — $1,000 held through that year became about $16,089 by year-end. Its weakest year was 2017, at -89.0%.
Does the calculator include dividends and splits?
Yes where available. Prices are adjusted for both stock splits and reinvested dividends (total return), the same measure brokerages use.
How much would $100 per month in TNDM have grown?
Investing $100 at the end of every month since 2013-11 would have grown to about $12,819 on $15,500 invested.
Did TNDM beat the S&P 500?
Over the same period, $1,000 in the S&P 500 with dividends reinvested (the S&P 500 Total Return index) would be worth $5,349. TNDM trailed the S&P 500 by +98.3% in total return.
Is this investment advice?
No. Wall Street Regrets is an entertainment and education tool. Every number is a historical calculation, not a prediction, and past performance never guarantees future results.
Methodology
Tandem Diabetes Care, Inc. (TNDM) historical total-return data from 2013-11 to 2026-09, reduced to month-end closes for the tables above.
Returns use adjusted close prices — adjusted for stock splits and reinvested dividends, the same convention used by major brokerages. End-of-day and live prices come from EODHD; parts of the deep historical series are carried over from Yahoo Finance data. A "year" scenario invests $1,000 at the prior December's month-end close and values it at the latest available month-end close. Non-USD amounts are converted at historical month-end exchange rates (EODHD): to USD on the buy date and back to your currency at the latest rate, so the return reflects the currency move as well as the asset.
Month-end resolution means intra-month extremes are not captured in tables; the calculator uses exact trading-day closes where daily data is available. Figures ignore taxes, fees, and the currency effects of non-USD listings. History is not a forecast. Wall Street Regrets is entertainment, not investment advice.
What if you'd held…
Data: adjusted close prices via EODHD and Yahoo Finance. As of 2026-09-04. Not financial advice.