[Solved]-Formatting Negative Numbers with Dollar Sign in Highcharts-Highcharts

you can switch to the pointformatter function to format it this way.

for example (jsfiddle):

pointformatter: function() {
    var isnegative = this.y < 0 ? '-' : '';
    return 'year ' + this.x.tofixed(0) + ': ' + isnegative + '$' + math.abs(this.y.tofixed(0));
}