If the company is a joint-stock enterprise that has issued shares, then the shares donated or purchased by employees are internal shares or original shares of the enterprise, and employees belong to shareholders in a certain form; But if the company only gives or lets employees buy shares issued to the outside world, it is not.
If a company does not issue shares, it is not a joint-stock enterprise. If the company gives or requires employees to buy shares, it shall be regarded as the investment of employees. Employees enjoy the rights and benefits enjoyed by shareholders or investment partners of the company.
Whether the company can use this as an excuse to dismiss employees and whether the shares held by employees are valid depends on the negotiation between employers and employees or the subject matter of the contract.
It is impossible to prove too many rights and obligations only by the company system or company documents.