Any phone buffs here?

I'm thinking of rooting my android phone but i do a lot of financial activity on my phone such as banking, buying and selling shares among other things. I don't want to jeopardize the security of my phone if rooting does that.

As an Australian i feel really uncomfortable talking about "rooting" my phone, but would appreciate any assistance. I would not be downloading after-market apps. Are these the only security risk when it comes to rooting?