$re = '/\b49=[^|]+/m';
$str = '8=FIXT1.1|9=709|35=y|34=53|49=DUMMYBROKER|56=<client_ID>|52=20210211- 12:12:37.358847|55=AUD/CAD|55=AUD/CHF|55=AUD/JPY|55=AUD/NZD|55=AUD/USD|55= CAD/CHF|55=CAD/JPY|55=CHF/JPY|55=EUR/AUD|55=EUR/CAD|55=EUR/CHF';
preg_match_all($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