The page referenced below might offer some answers to your questions. In your Hungarian source text you might want to look for key terms such as "üzletrész" (share) - "részesedés" (quota) - "érdekeltség" (interest). I don't see why one "share" would mean 100% of the registered capital (jegyzett tőke) of said company. It would be helpful to see the exact sentence from the source text that you have difficulty translating.

"Company limited by shares (Rt)
An Rt is established with a predetermined amount and nominal value of shares. The liability of its members is limited to the provision of the nominal or issue value of the shares.

An Rt may be established via a private offering (its shares are offered only to its founders) or a public offering (its shares are offered to the public). The difference must be indicated in the company's name as “Zrt” (private) or “Nyrt” (public).

Shares are securities that embody a shareholder's membership rights in the company. Only private Rts may issue printed share certificates, public Rts may only have dematerialized shares (registered in the shareholders security account held by a financial institution).

Shares may be (i) ordinary shares, (ii) employee shares, (iii) interest-bearing shares, (iv) redeemable shares. or (v) preference shares, which have the following sub-categories:
- dividend preference shares
- preference with respect to the liquidation ratio
- preference with respect to voting rights
- (only in the case of private Rts) preference with respect to the appointment of executive officers or members of the supervisory board
- (only in the case of private Rts) shares ensuring pre emption rights"