$re = '/Владелец: (\w+_\w+)/m';
$str = 'style="top:813.166px;left:830.066px;background:url(/images/business_0.gif)" title="<div class=\'text-center\'>Амуниция/Тир<br><br>Владелец: Richard_Universe</div>" data-toggle="tooltip" data-html="true"></div><div class="map-icon business-state-0 business-not-sale" style="top:558.291px;left:1013.365px;background:url(/images/business_0.gif)" title="<div class=\'text-center\'>Амуниция/Тир<br><br>Владелец: Brake_Blame</div>" data-toggle="tooltip" data-html="true"></div><div class="map-icon business-state-0 business-not-sale" style="top:603.893px;left:616.15px;background:url(/images/business_0.gif)" title="<div class=\'text-center\'>Амуниция/Тир<br><br>Владелец: Queens_Nakamura</div>" data-toggle="tooltip" data-html="true"></div><div class="map-icon business-state-1
';
preg_match_all($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