If your data really looks like this...

["2007/12/18", "34.6400", "35.0000", "34.2100", "34.7400"],
["2007/12/19", "34.6900", "35.1400", "34.3800", "34.7900"],
["2007/12/20", "35.2900", "35.7900", "35.0800", "35.5200"],
[download]

...and i understood you right i would try something like this:

#!/usr/bin/env perl

use strict;
use warnings;
use Data::Dump;
use Path::Tiny;

my $data = path("data.txt")->slurp;

# $data = qq(\($data\));

$data = qq{($data)};

my @data = eval($data);

dd \@data;

__END__

karls-mac-mini:monks karl$ ./slowandsteady.pl
[
  ["2007/12/18", "34.6400", "35.0000", "34.2100", "34.7400"],
  ["2007/12/19", "34.6900", "35.1400", "34.3800", "34.7900"],
  ["2007/12/20", "35.2900", "35.7900", "35.0800", "35.5200"],
]
[download]

See also perldsc, eval and Path::Tiny for further information.

Edit: Removed frivolous escapades.

Best regards, Karl