What is the expansion of SEBI?

It stands for "Securities and Exchange Board of India (SEBI)"

Securities and Exchange Board of India (SEBI) is a board (autonomous body) created by the Government of India in 1988 and given statutory form in 1992 with the SEBI Act 1992 with its head office at Mumbai. It is chaired by Mr. M. Damodaran a respected turnaround civil servant credited with turning around large public sector companies from near death scenarios including the famous Unit Trust of India. Below the Board, headed by the Chairman, the staff/officers of the organization are led by Executive Directors.

Sebi has three functions rolled into one body: legislative, judicial and executive. It drafts rules in its legislative capacity, it conducts enquiries and enforcement action in its executive fuction and it passes rulings and orders in its judicial capacity. Though this makes it exceedingly powerful, there is an appeals process to create accountibility.

Sebi has had a mixed history in terms of its success as a regulator. Though it has pushed systemic reforms aggresively and successively (e.g. the quick movement towards making the markets electronic and paperless), it seems to lack the legal expertise needed to sustain prosecutions/enforcement actions. It has often received flack from the appellate body known as the Securities Appellate Tribunal (SAT). From the SAT, an appeal lies straight to the Supreme Court of India.

Functions
Its main functions are providing for

regulating the business in stock exchanges and any other securities markets
registering and regulating the working of stock brokers, sub-brokers, share transfer agents, bankers to an issue, trustees of trust deeds, registrars to an issue, merchant bankers, underwriters, portfolio managers, investment advisers and such other intermediaries who may be associated with securities markets in any manner.
registering and regulating the working of the depositories, participants, custodians of securities, foreign institutional investors, credit rating agencies and such other intermediaries as the Board may, by notification, specify in this behalf.
registering and regulating the working of venture capital funds and collective investment schemes including mutual funds;
promoting and regulating self-regulatory organisations;
prohibiting fraudulent and unfair trade practices relating to securities markets;
promoting investors' education and training of intermediaries of securities markets;
prohibiting insider trading in securities;
regulating substantial acquisition of shares and takeover of companies;
calling for information from, undertaking inspection, conducting inquiries and audits of the stock exchanges, mutual funds and other persons associated with the securities market and intermediaries and self- regulatory organisations in the securities market;
calling for information and record from any bank or any other authority or board or corporation established or constituted by or under any Central, State or Provincial Act in respect of any transaction in securities which is under investigation or inquiry by the Board;19
performing such functions and exercising such powers under the provisions of [...]20 Securities Contracts (Regulation) Act, 1956, as may be delegated to it by the Central Government;
levying fees or other charges for carrying out the purpose of this section;
conducting research for the above purposes;
calling from or furnishing to any such agencies, as may be specified by the Board, such information as may be considered necessary by it for the efficient discharge of its functions;21
performing such other functions as may be prescribed