What if I had invested $100 a month in Sanofi
Investing a fixed amount every month, whatever the price: that is dollar-cost averaging. Here is what this strategy would have done in Sanofi, depending on the year you started.
Sanofi, a stock listed in Paris and quoted in euros, went nowhere in dollar terms: +27.1% between December 2003 and November 2026, +1.1% a year. For a monthly investor, 65% of the 275 monthly purchases made since December 2003 were below today's price.
Data: Yahoo Finance monthly closing prices, up to date as of (latest update November 5, 2026) MethodAuthor: Yann Avondo
If I had invested $100 every month in Sanofi since January 2016, today I would have $13,407
Over the same period
Worst moment: −28.3% between September 2024 and September 2026. To get this result, you had to hold on without selling.
Sanofi at a glance
Sanofi is France’s largest drugmaker, driven notably by the anti-inflammatory Dupixent and vaccines. The stock long moved sideways, partly offset by a high dividend.
The worst drop from a peak reached 46.8% in dollar terms (June 2006 to February 2009), erased by March 2013. Over the same period, the MSCI World (price index) returned +7.0% a year in dollar terms: Sanofi lagged well behind. Calendar year after calendar year, 12 of 22 ended higher; the best, 2012, returned +28.4%, the worst, 2008, cost 31.0%.
$100 a month in Sanofi, by start year
One contribution at the start of each month since January of the given year, valued at the latest price. Click a year for the full story.
| Start | Invested | Worth today | Multiple | Annual IRR |
|---|---|---|---|---|
| $2,300 | $2,291 | ×1 | −0.4% | |
| $3,500 | $3,416 | ×0.98 | −1.6% | |
| $4,700 | $4,538 | ×0.97 | −1.7% | |
| $5,900 | $5,732 | ×0.97 | −1.2% | |
| $7,100 | $6,886 | ×0.97 | −1.0% | |
| $8,300 | $8,063 | ×0.97 | −0.8% | |
| $9,500 | $9,378 | ×0.99 | −0.3% | |
| $10,700 | $10,739 | ×1 | +0.1% | |
| $11,900 | $11,993 | ×1.01 | +0.2% | |
| $13,100 | $13,407 | ×1.02 | +0.4% | |
| $14,300 | $14,583 | ×1.02 | +0.3% | |
| $15,500 | $15,686 | ×1.01 | +0.2% | |
| $16,700 | $16,810 | ×1.01 | +0.1% | |
| $17,900 | $18,274 | ×1.02 | +0.3% | |
| $19,100 | $19,867 | ×1.04 | +0.5% | |
| $20,300 | $21,598 | ×1.06 | +0.7% | |
| $21,500 | $23,423 | ×1.09 | +0.9% | |
| $22,700 | $25,035 | ×1.1 | +1.0% | |
| $23,900 | $26,342 | ×1.1 | +1.0% | |
| $25,100 | $27,604 | ×1.1 | +0.9% | |
| $26,300 | $28,990 | ×1.1 | +0.9% | |
| $27,500 | $30,648 | ×1.11 | +0.9% |
Lump sum or DCA in Sanofi?
Since January 2016, investing in Sanofi all at once (lump sum) multiplied the stake by ×1.11, +1.0% a year. Investing every month (DCA) multiplied the total contributions by ×1.02, an annual return (IRR) of +0.4%.
Here the lump sum did better: money invested early rode the whole rise. That is the most common outcome on an asset that goes up.
Frequently asked questions
How much would I have if I had invested $100 a month in Sanofi for 10 years?
Investing $100 every month since January 2016, $13,100 in total, would be worth about $13,407 today: an annual return (IRR) of +0.4% (price only, in the displayed currency).
What if I had started investing $100 a month in Sanofi in 2015?
Since January 2015, $14,300 invested in total would be worth about $14,583 today (IRR of +0.3% a year).
What if I had started investing $100 a month in Sanofi in 2020?
Since January 2020, $8,300 invested in total would be worth about $8,063 today (IRR of −0.8% a year).
Is investing monthly better than investing all at once?
Historically, investing a lump sum right away returns more in most cases, because markets rise more often than they fall. But monthly investing smooths the purchase price, protects against the worst timing and matches how people actually save: from their paycheck, month after month.
How is the annual return calculated?
With spread-out contributions, the multiple of the amount invested does not tell the whole story: the last dollars had only a few months to grow. The IRR (internal rate of return) is the average annual return that, applied to each contribution from its date, produces the final value.
Compare with
Before you have regrets
What this calculation does not tell you.
Hindsight bias
Picking Nvidia or Bitcoin today means picking known winners. Back then, nothing set them apart from hundreds of assets that went nowhere or vanished.
Holding on was the real test
The result assumes you never sold, including through the drawdowns shown above. Very few investors actually do.
The broad market, no bet required
The MSCI World never makes headlines, but it does not require guessing the winner. It is the fairest yardstick for any pick.
Method: past performance, computed from split-adjusted monthly closing prices (intra-month lows are smoothed out). Converted at each month’s exchange rate; no fees, no taxes. The MSCI World benchmark is the price index, excluding dividends. Sources: Yahoo Finance (prices, exchange rates, US Treasury bills), Eurostat (inflation), published regulated rates (Livret A). Not investment advice. NokxiHub.