What if you'd held SPRO?
A $1,000 investment in Spero Therapeutics, Inc. (SPRO) at the month-end close of 2017-11 would be worth $103 at the close of 2026-08 — -89.7% total return, dividends reinvested. The same $1,000 in the S&P 500 would be worth $2,911.
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 2026-08, dividends included.
Every year, $1,000 from 2017
| Year | Value of $1,000 | Year return |
|---|---|---|
| 2017 | $1,000 | — |
| 2018 | $523 | -47.7% |
| 2019 | $818 | +56.3% |
| 2020 | $1,650 | +101.7% |
| 2021 | $1,363 | -17.4% |
| 2022 | $147 | -89.2% |
| 2023 | $125 | -15.0% |
| 2024 | $87.66 | -29.9% |
| 2025 | $198 | +126.2% |
| 2026 | $105 | -47.2% |
Best and worst month-end to buy
The best single month-end close to have bought SPRO was 2025-04 ($0.66): $1,000 then is $1,869 today. The worst was 2020-12 ($19.39): $1,000 then is $63.43.
FAQ
What would $1,000 in SPRO be worth today?
A $1,000 investment in Spero Therapeutics, Inc. (SPRO) at the start of 2017 would be worth about $103 today, a total return of -89.7%. Dividends are reinvested in these figures.
What were the best and worst years for SPRO?
Spero Therapeutics, Inc. (SPRO)'s strongest calendar year since 2017 was 2025, a +126.2% return — $1,000 held through that year became about $2,262 by year-end. Its weakest year was 2022, at -89.2%.
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 SPRO have grown?
Investing $100 at the end of every month since 2017-11 would have grown to about $5,149 on $10,600 invested.
Did SPRO beat the S&P 500?
Over the same period, $1,000 in the S&P 500 index would be worth $2,911. SPRO trailed the S&P 500 by +96.5% 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
Spero Therapeutics, Inc. (SPRO) historical total-return data from 2017-11 to 2026-08, reduced to month-end closes for the tables above.
Returns use adjusted close prices from Yahoo Finance historical data — adjusted for stock splits and reinvested dividends — the same convention used by major brokerages. 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 (Yahoo Finance): 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 Yahoo Finance. As of 2026-08. Not financial advice.