$re = '/(?<=symbol\=)[\w\d-]+(?=&|\n)/';
$str = 'https://www.set.or.th/set/companyholder.do?symbol=EMC
https://www.set.or.th/set/companyholder.do?symbol=EMC&language=th&country=TH
https://www.set.or.th/set/companyholder.do%3Bjsessionid=B08A576398DF62A466D1D08EAAF280CC?symbol=BLAND-F&language=en&country=EN
https://www.set.or.th/set/newsdetails.do?newsId=14828768298911&language=th&country=TH
https://www.set.or.th/set/companyholder.do?symbol=RML-F&ssoPageId=6&language=th&country=TH';
preg_match_all($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