Reading 24 Yield Curve Strategies Example 8 Assessing Risk of Yield Curve Movements

Hi people, I have tried going through this example for quite some time and I still don’t really understand what it meant by “a Positive one Standard Deviation Move” on the yield curve.

_ "The first step is to calculate the impact of each of the three main types of yield curve movements - each one a positive one standard deviation move - on the value of each portfolio. _

_ Summarize and explain the pattern of returns resulting from each type of movements." _

Solution to the question gave a 1. Positive shift in yield curve, 2. Flattening twist & 3. Positive Butterfly

How does a “Positive one Standard Deviation Move” translate to 1. Positive shift in yield curve, 2. Flattening twist & 3. Positive Butterfly?

Thank you.

Best Regards, Nirnek