There is a difference between what an individual investor and a brokerage house has to hold in regards to options. Yes, the individual does have to have a deposit. Brokerage houses do not. Thus they can get away with selling naked shorts and that is how you end up with shorts that exceed the value of the company.
For your reading pleasure and enlightenment:
(5) Specialists' and Market Makers' Accounts
(A) A member may carry the account of an "approved specialist or market maker," which account is limited to specialist or market making transactions, upon a margin basis which is satisfactory to both parties. The amount of any deficiency between the equity in the account and the haircut requirements pursuant to SEC Rule 15c3-1 shall be charged against the member's net capital when computing net capital under SEC Rule 15c3-1. For the purpose of this subparagraph, the term "approved specialist or market maker" means either: i. a specialist or market maker, who is deemed a specialist for all purposes under the Act and who is registered pursuant to the rules of a national securities exchange; or ii. an OTC market maker or third market maker, who meets the requirements of Section 220.7(g)(5) of Regulation T.
(B) In the case of a joint account carried by a member in accordance with subparagraph (i) above in which the member participates, the equity maintained in the account by the other participants may be in any amount which is mutually satisfactory. The amount of any deficiency between the equity maintained in the account by the other participants and their proportionate share of the haircut requirements pursuant to SEC Rule 15c3-1 shall be charged against the member's net capital when computing net capital under SEC Rule 15c3-1.
(6) Broker/Dealer Accounts
(A) A member may carry the proprietary account of another broker/dealer, which is registered with the Commission, upon a margin basis which is satisfactory to both parties, provided the requirements of Regulation T and Rules 400 through 406 under the Act and Rules 41.42 through 41.48 under the CEA are adhered to and the account is not carried in a deficit equity condition. The amount of any deficiency between the equity maintained in the account and the haircut requirements pursuant to SEC Rule 15c3-1 shall be charged against the member's net capital when computing net capital under SEC Rule 15c3-1.