my @brokerElements = split /\s+/, $brokerLine;
push @brokers, $lineElements[0];
# ...
my @tickerElements = split /\s+/, $tickerLine;
my $broker = $tickerElements[1];
my $ticker = $tickerElements[3];
my $broker_regex = quotemeta $broker;
if (grep /^$broker_regex$/i, @brokers)
{
    $tickerInfo{$broker} = $ticker;
}
# ...
foreach my $reportBroker (sort keys %tickerInfo)
{
    print "Broker $reportBroker has ticker $tickerInfo{$reportBroker}\n";
}