You are overwriting your hash every time through the while loop. Move the declaration of the hash outside of the loop:

    my $csv = Text::CSV_XS->new();
    open (FILE, "<", "$tickdir/$file") or die "Can't open CSV File:$! 
+\n";

    my %HOH;
    while (<FILE>) {
        $csv->parse($_);
        my @columns = $csv->fields();
        my $key = str2time($columns[1].' '.$columns[2]);
        my (@prices, @volumes) = ();

        $HOH{$key}{"name"} = $columns[0];
        push(@{$HOH{$key}{"price"}}, $columns[3]);
        push(@{$HOH{$key}{"volumes"}}, $columns[4]);

        print Dumper(\%HOH);
    }
    close FILE;
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