Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Is it unreasonable to double your investment year over year?
Yes. The definition of unreasonable shows as "not guided by or based on good sense." 100% years require a high risk. Can your one stock double, or even go up three fold? Sure, but that would likely be a small part of your portfolio. Overall, long term, you are not likely to beat the market by such high numbers.  That said, I had 2 years of returns well over 100%. 1998, and 1999. The S&P was up 26.7% and 19.5%, and I was very leverage in high tech stock options. As others mentioned, leverage was key. (Mark used the term 'gearing' which I think is leverage). When 2000 started crashing, I had taken enough off the table to end the year down 12% vs the S&P -10%, but this was down from a near 50% gain in Q1 of that year. As the crash continued, I was no longer leveraged and haven't been since. The last 12 years or so, I've happily lagged the S&P by a few basis points (.04-.02%).  Also note, Buffet has returned an amazing 15.9%/yr on average for the last 30 years (vs the S&P 11.4%). 16% is far from 100%. The last 10 year, however, his return was a modest 8.6%, just .1% above the S&P.