I have already had a question asked about redirection from the domain aliases to the main domain here previously, but here is some stats:
in last seven days before registration of this new domain aliases 42000 out of which 22000 was US traffic from Google,
in last seven days after registration of this domain aliases 26000 out of which 11000 was US traffic from Google
other engines seems to be pretty much the same as it was.
Now the question could this be down to the registration of this new aliases?