How to pronounce the greece letter "standard deviation "

[Londondrug]

Volatility, or the square root of variance. standard deviation.
For example , I know E(X) can be pronounced as "Miu X"
but don't know how to pronounce correctly for V(X)^.5

[Gandalf]

is "sigma", pronounced as you would expect those letters to be pronounced. In particular, like the word "stigma" but without the t.

[Londondrug]

Thank you, Gandalf.