Mayor Shareholder

Shares start to be sold mid way through the 2nd part of the campaign. You'll have to participate in a share auction before every level. Just make sure you win every time. Note the price the NPC competitors buy at is pretty random, and you can retry any number of times just by quitting out to the main menu and then going back in to Continue game; as it tells you repeatedly going back to the main menu loses all progress since reaching town. (so do this first on getting into town so you don't have to redo any other purchases or the land auction). It will be very hard to do this at the same time as Filthy Rich or Millionaire - so don't. Go for this in your first playthrough (non-expert!), and the others in the Expert playthrough following it.