First off, we’re changing up the holding systems. You don’t have holdings, you have Special Purpose Entities, a sort of shell company formed for the purpose of administering a particular task with a degree of financial independence and for hiding your vast quantities of debts should you acquire them (in order to disavow ownership of them.) Most often for simplicity, these are called Firms (or I guess you can continue calling them Holdings if you’re a purist.)
You can have one of each type of Firm per level of your Company. Firms acquired through Hostile Takeovers don’t count towards this limit, as they are purchased with the infrastructure to administrate them already installed.
There are three types of Firms: Security Firms provide military might and access to the corporate monopoly on violence, Temple Firms administrate and control the populace to reduce the frequency of Unrest and provide access to the levers of religious power, and Trade Firms extract resources, manage industrial production, and actually generate profit.
When you form a Firm by paying the necessary fees and doing the necessary paperwork to incorporate it from scratch, you own 100% of its Stocks, ten out of ten. In times of crisis, calming the board necessitates the issuing of new stocks, diluting your controlling share with free stocks on the market. When a Firm gains a point of Unrest, one Stock you own is put up on the market for sale. You can buy it back at market price, or take Actions that reduce Unrest (and reclaim issued free Stocks if any are unpurchased), but if you don’t do either of these things they are available for purchase by other players and NPCs. Ownership of stocks is secret information, but can be discovered through corporate espionage.
You can also liquidate stocks on purpose- put any number of stocks on the open market and receive the gp from the winning bid (minus a market fee of course.)
Stocks are bid on each season. Each stock on the open market begins at a price of 10gp. Players may place secret bids on stocks, know if they are the current highest bid, and are informed when they are not. At the change of the season, the highest bid pays the fee to the market and acquires the stock.
Each foreign stock (not one you initially offered) provides 1d10gp each Spring in dividends. Controlling one Stock of a Firm lets you ask questions about its activities and properties and get reliable answers. Controlling five lets you perform a Hostile Takeover, buying out the remaining stocks at a significant discount and folding the Firm into your own Corporate family.
Things other than Firms are available on the market as well- the Calendar of Four Suns proscribes certain times of pain and elevation for all members of the Jaguar Empire, and you can sell and buy rights and responsibilities as easily as you can trade artisan goods, food, raw materials, or tributary towns.