not via marketshare

That's not an entirely fair measure though, considering Microsoft lost an antitrust case that was brought because they were unfairly leveraging their monopoly in operating systems to give them an advantage in browser adoption. The DOJ threatened to break up Microsoft over it, and eventually only stopped when Microsoft added an option for users to pick a difference default browser over IE.

By that time IE's dominance was beyond Mozilla's reach and it was only when Google leveraged their monopoly in online advertising that a real alternative option for users became viable.

https://en.wikipedia.org/wiki/United_States_v._Microsoft_Cor....