How to display balloons in all brands in google maps without having to click?

I have the following code to display information for a specific bookmark:

var bindInfoWindow = function (marker, map, infowindow, htmlContent) {
            google.maps.event.addListener(marker, 'click', function () {
                infowindow.setContent(htmlContent);
                infowindow.open(map, marker);

            })
 }; 

It works fine if I click.

Now, how do I display information for all bookmarks without having to click?

I tried to remove the click function (see below), but it only shows the last loaded marker.

var bindInfoWindow = function (marker, map, infowindow, htmlContent) {
                infowindow.setContent(htmlContent);
                infowindow.open(map, marker);
            };

How do I resolve this?