GROUP ONE TRADING, L.P. Information

440 S. LASALLE STREET, CHICAGO, Illinois, 60605, (312) 431-2841

Report Date: 03/31/2013

Position Statistics:

Total Positions 1,732
New Positions 449
Increased Positions 906
Decreased Positions 806
Positions with Activity 1,712
Sold Out Positions 433
Total Mkt Value
(in $ millions)
468

Sector Weighting

Basic Materials 7.86%
Capital Goods 2.18%
Conglomerates 0.75%
Consumer Cyclical 2.76%
Consumer/Non-Cyclical 5.55%
Energy 12.85%
Financial 14.22%
Healthcare 12.34%
Services 20.45%
Technology 18.15%
Transportation 1.4%
Utilities 1.02%

Institutional Holdings information is filed by major institutions on form 13-F with the Securities and Exchange Commission.

906 INCREASED Positions as of 03/31/2013

Company Class Value of Shares ($1,000s) Change in Value ($1,000s) Change (%) Shares Held
DELL INC COM 12,310 12,246 19,379.03 913,177
CONSTELLATION BRANDS INC CL A 11,105 4,802 76.18 211,169
OCWEN FINL CORP COM NEW 8,906 8,906 New 197,377
NEWS CORP CL A 8,796 8,796 New 278,717
NEWFIELD EXPL CO COM 8,622 8,593 29,986.30 360,133
ARBITRON INC COM 8,531 7,959 1,390.68 182,087
VODAFONE GROUP PLC NEW SPONS ADR NEW 7,761 7,200 1,283.12 270,316
NOKIA CORP SPONSORED ADR 7,496 7,062 1,630.68 1,941,861
NATIONSTAR MTG HLDGS INC COM 7,270 4,181 135.33 168,603
JIVE SOFTWARE INC COM 5,826 5,787 14,918.51 335,964
FREEPORT-MCMORAN COPPER & GOLD COM 5,420 3,902 257.02 183,608
ZHONGPIN INC COM 5,246 2,217 73.19 392,661
GENWORTH FINL INC COM CL A 5,200 3,207 160.95 456,512
ACADIA PHARMACEUTICALS COM 4,866 2,611 115.80 264,028
COBALT INTL ENERGY INC COM 4,642 3,534 318.84 174,263
AEGERION PHARMACEUTICALS INC COM 4,575 1,424 45.18 71,817
AMERICAN CAP LTD COM 4,574 3,390 286.54 346,223
MBIA INC COM 4,482 3,017 205.90 325,487
NORTHERN TIER ENERGY LP COM UN REPR PART 4,375 4,375 New 170,443
MICHAEL KORS HLDGS LTD SHS 4,289 992 30.07 69,600