use strict;
use warnings;
while(<DATA>)	{	
	chomp;
	$_=~s/(\d{5} \w+)/ \1\n/g;
	print;
}

__DATA__
Some Company; Some Street 52
12345 City1
Another Company; Another Street 63
23456 City2
Yet Another Company; New Street 11
34546 City3