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“Only buy something that you’d be perfectly happy to hold if the market shut down for 10 years.”

— Warren Buffett

Investors can learn a lot from Warren Buffett, whose above quote teaches the importance of thinking about investment time horizon, and asking ourselves before buying any given stock: can we envision holding onto it for years — even a decade-long holding period possibly?

Suppose a “buy-and-hold” investor was considering an investment into Merck & Co Inc (NYSE: MRK) back in 2015: back then, such an investor may have been pondering this very same question. Had they answered “yes” to a full decade-long investment time horizon and then actually held for these past 10 years, here’s how that investment would have turned out.

Start date: 12/16/2015
$10,000

12/16/2015
  $26,474

12/15/2025
End date: 12/15/2025
Start price/share: $51.55
End price/share: $100.26
Starting shares: 193.99
Ending shares: 264.16
Dividends reinvested/share: $24.76
Total return: 164.84%
Average annual return: 10.22%
Starting investment: $10,000.00
Ending investment: $26,474.98

As shown above, the decade-long investment result worked out quite well, with an annualized rate of return of 10.22%. This would have turned a $10K investment made 10 years ago into $26,474.98 today (as of 12/15/2025). On a total return basis, that’s a result of 164.84% (something to think about: how might MRK shares perform over the next 10 years?). [These numbers were computed with the Dividend Channel DRIP Returns Calculator.]

Notice that Merck & Co Inc paid investors a total of $24.76/share in dividends over the 10 holding period, marking a second component of the total return beyond share price change alone. Much like watering a tree, reinvesting dividends can help an investment to grow over time — for the above calculations we assume dividend reinvestment (and for this exercise the closing price on ex-date is used for the reinvestment of a given dividend).

Based upon the most recent annualized dividend rate of 3.4/share, we calculate that MRK has a current yield of approximately 3.39%. Another interesting datapoint we can examine is ‘yield on cost’ — in other words, we can express the current annualized dividend of 3.4 against the original $51.55/share purchase price. This works out to a yield on cost of 6.58%.

Here’s one more great investment quote before you go:
“A market downturn doesn’t bother us. It is an opportunity to increase our ownership of great companies with great management at good prices.” — Warren Buffett