Create an additional sub rule for the Production rule called Advertising, with the following text:

Advertising costs resources to put into place. Whenever a unit of Advertising is produced, its new owner loses $3M in cash. When time is advanced, Advertising adds 1 to the owning corporations Cash production. The corporation that owns the most units of Advertizing gains $2M in addition to their normal cash production when time is advanced. If no corporation has the most units (a tie) then no one gains this bonus.

The production rights for Advertising are in the Public Domain.