// CONTROLLER
        $selectedShareEntities = ShareHolder::where('client_id', $clientId)->get()->pluck('entity_id');

        return view('shares.shareholders.show', [
            'selectedShareEntities' => $selectedShareEntities
        ]);

// BLADE
<div class="">
  <label class="required-field">Share Entity</label>
   {!! Form::select('entity_id[]', $shareEntities, $selectedShareEntities, ['id' => 'shareEntities', 'multiple' => 'multiple']) !!}
</div>