why ASX?, page-15

and to answer your question about why not Nasdaq, this has been one of the most asked RTO questions I've seen (for all those tech US based companies).

its a simple answer, Nasdaq has a set of requirements for listing in which BUD hasn't met yet
BUD would need either
a) $11m USD in earnings for the past three years
b) Revenue of more than $27.5m USD + a market cap of $550m USD for the past 3 years
c) Revenue of more than $90m USD + a market cap of over $850m USD for the past year
d) Market cap of $160m USD + Assets of over $80m USD

as you can see, pre-requisites for listing in Nasdaq are high, so companies like BUD will raise money via the ASX, build themselves up to attain the above prerequisites, and eventually dual list in the Nasdaq .