[Homer]

Lets say I experience a 2.4SD downswing, how can I calculate the liklyhood of that happening?

I'm not sure exactly what you're asking, so I'll provide the answer to a couple different questions (with the assistance of Excel).

1) What is the probability of experiencing a 2.4 SD loss or worse?

<font color="blue">=normsdist(-2.4)</font>

2) What is the probability of experiencing a 2.4 SD swing or worse (&lt;=-2.4 SD or &gt;=2.4 SD)?

<font color="blue">=2*normsdist(-2.4)</font>

3) What is the probability of experiencing a swing of 2.4 SD of less (-2.4 SD to 2.4 SD)?

<font color="blue">=1-2*normsdist(-2.4)</font>

-- Homer