gistfile1.txt

add_shortcode( 'wplfdynamicselect', 'wpfi_wplf_dynamic_select' );
function wpfi_wplf_dynamic_select( $atts ) {

  $the_query = new WP_Query( array(
    'post_type'               => 'CPT',
    'post_status'             => 'publish',
    'posts_per_page'          => 100,
    'order'                   => 'DESC',
    'orderby'                 => 'title',
    'no_found_rows'           => true,
    'update_post_meta_cache'  => false,
    'update_post_term_cache'  => false
  ) );

  if( $the_query->have_posts() ):
    $return = '<select name="company">';

    while( $the_query->have_posts() ):
      $the_query->the_post();
      $return .= '<option value="'.get_the_id().'">'.get_the_title().'</option>';
    endwhile;

    $return .= '</select>';
  endif;

  wp_reset_postdata();
  return $return;
}