The average value return is in the nature of asymmetry.

均值回归具有不对称性；

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But, in recent years, Average Value Return Theory gave a challenge to the Random Walk Theory.

但是，近年来均值回归理论对随机漫步理论提出了挑战。

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Declining rates pushed up the value of bond investments, delivering an average 9.3% return for Treasury bond mutual funds.

FORBES: Playing The Big Bond Meltdown Without Getting Burned

Snowling ticks off other advantages for Sallie: low interest rate risk (given government guarantees), profit growth expectations in the 15% range, a rich return on equity (net income divided by average book value) of 38%, and a cheap valuation relative to history and the broader market.

FORBES: Thanks To The Democrats: Sallie Looks Cheap