* Q4 loss/shr $0.66 vs est EPS $0.16
* Q4 total revenue down 7 pct
* DARTs up 9 pct
* Shares up 2 pct in extended trading
Jan 20 Derivative trader Interactive Brokers Group Inc (IBKR.O) swung to a surprise quarterly loss on a steep fall in revenue from its market-making segment.
Net loss available to common shareholders was $28.1 million, or 66 cents a share, compared with a net income of $2.3 million, or 6 cents a share, a year ago.
Analysts expected the company to earn 16 cents a share, according to Thomson Reuters I/B/E/S.
Net revenue from the company's market-making segment, which handles over a million trades per day, was $44 million, compared with $75.2 million, a year ago.
Market makers fulfil buy and sell orders from brokers, and create a marketplace for the buying and selling of shares to match supply and demand by using its own inventory or seeking offsetting orders.
During the quarter, Interactive's cleared daily average revenue trades (DARTs) -- a key measure of trading activity for retail brokerage firms -- rose 9 percent to 337,000.
Total revenue was $186.3 million, compared with $200.4 million a year ago.
Analysts expected revenue of $251.2 million.
The company's electronic-broker segment competes with the broker arm of TradeStation Group Inc TRAD.O, while its market-making segment competes with a unit of Citigroup (C.N).
Shares of the Greenwich, Connecticut-based company closed at $17.48 on Thursday on Nasdaq. They were up 2 percent at $17.77 in extended trading. (Reporting by Mayuresh Tungare in Bangalore; Editing by Maju Samuel)