Over a two-year period, a 30% gain is certainly in the realm of what’s considered normal. I’ll spare you the statistics lesson, but a gain of as much as 45.2% or a loss of as much as 22.8% in any single year are both not statistically unusual. And the market’s performance has been outside of these bounds twice in the past 50 years, so even this isn’t a guaranteed range.

The market could conceivably rise by 30% this year, fall 20% next year and rise another 40% in 2020.

Having said that, stocks are surprisingly predictable over long periods of time, say 20 years or more. Over a period of 20-plus years, the major stock indexes have generated annualized total returns of 9% to 11%, depending on the time you’re looking at.

The S&P 500 has had two nine-year stretches over the past 50 years where the index produced positive total returns every year, including the one we’re still experiencing.

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