$re = '/<td\s.*?>.*?<span\s.*?>(.*?)<\/span><\/td>/m';
$str = '<td id="yiv9101838563i4" style="padding:0;padding-top:25px;font-family:\'Segoe UI\', Tahoma, Verdana, Arial, sans-serif;font-size:14px;color:#2a2a2a;">Security code: <span style="font-family:\'Segoe UI Bold\', \'Segoe UI Semibold\', \'Segoe UI\', \'Helvetica Neue Medium\', Arial, sans-serif;font-size:14px;font-weight:bold;color:#2a2a2a;">7201</span></td>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php