Charitynavigator has this to say about Against Malaria Foundation: "This organization is not eligible to be rated by Charity Navigator because it does not meet our criterion of having nontrivial fundraising expenses."
Oddly, they don't even include Charity Navigator among their six chosen sources.
As you can see GiveWell has investigated AMF including its finances in vastly more detail over 4 years than Charity Navigator has ever investigated anyone: http://www.givewell.org/charities/against-malaria-foundation
If all of that 92% is actually going directly to programs, that's excellent.
However, IIRC all the fundraising and admin costs are covered by separate donors so that any additional donations go to nets. AMF doesn't have much of a fundraising operation as it gets its funding through GiveWell and Good Ventures primarily.
it's a good thing for charities to spend more on fundraising than they do
What raises concern for me is when the percentage of receipts spent on fundraising is disproportionately high and/or spent on overpaid insider salaries.