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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 ten year 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 ten year investment into the stock back in 2015.

Start date: 11/09/2015
$10,000

11/09/2015
  $5,340

11/06/2025
End date: 11/06/2025
Start price/share: $293.40
End price/share: $156.74
Starting shares: 34.08
Ending shares: 34.08
Dividends reinvested/share: $0.00
Total return: -46.58%
Average annual return: -6.08%
Starting investment: $10,000.00
Ending investment: $5,340.49

The above analysis shows the ten year investment result worked out poorly, with an annualized rate of return of -6.08%. This would have turned a $10K investment made 10 years ago into $5,340.49 today (as of 11/06/2025). On a total return basis, that’s a result of -46.58% (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 piece of investment wisdom to leave you with:
“If you can follow only one bit of data, follow the earnings.” — Peter Lynch