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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

The Warren Buffett investment philosophy calls for a long-term investment horizon, where a decade-long holding period, or even longer, would fit right into the strategy. How would such a strategy have worked out for an investment into Biogen Inc (NASD: BIIB)? Today, we examine the outcome of a decade-long investment into the stock back in 2015.

Start date: 08/19/2015
$10,000

08/19/2015
  $4,304

08/18/2025
End date: 08/18/2025
Start price/share: $315.82
End price/share: $135.91
Starting shares: 31.66
Ending shares: 31.66
Dividends reinvested/share: $0.00
Total return: -56.97%
Average annual return: -8.08%
Starting investment: $10,000.00
Ending investment: $4,304.27

As shown above, the decade-long investment result worked out poorly, with an annualized rate of return of -8.08%. This would have turned a $10K investment made 10 years ago into $4,304.27 today (as of 08/18/2025). On a total return basis, that’s a result of -56.97% (something to think about: how might BIIB shares perform over the next 10 years?). [These numbers were computed with the Dividend Channel DRIP Returns Calculator.]

One more investment quote to leave you with:
“It’s not how much money you make, but how much money you keep.” — Robert Kiyosaki