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ION GEOPHYSICAL CORP
ION GEOPHYSICAL CORP. Institutional holdings reported to the SEC.

Institutional Holders (2014Q1)
Portfolio Summary: 174 Institutional holders with a total value of $441,893,970.
#
Manager Name
Shares
Value ($)
%
Options
Notes
101 THRIVENT FINANCIAL FOR LUTHERANS 46,550 196,000 0.04%
102 VIRGINIA RETIREMENT SYSTEMS ET Al 45,100 190,000 0.04%
103 PUBLIC EMPLOYEES RETIREMENT ASSOCIATION OF COLORADO 43,800 184,000 0.04%
104 UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 41,196 173,000 0.04%
105 SUSQUEHANNA INTERNATIONAL GROUP, LLP 39,800 168,000 0.04% Put
106 Aperio Group, LLC 38,006 160,000 0.04%
107 SHEPHERD KAPLAN KROCHUK, LLC 37,800 159,000 0.04%
108 Nine Chapters Capital Management LLC 36,800 155,000 0.04%
109 BlackRock Japan Co. Ltd 36,520 154,000 0.03%
110 TWO SIGMA ADVISERS, LP 34,696 146,000 0.03%
111 DEARBORN PARTNERS LLC 32,300 136,000 0.03%
112 PineBridge Investments, L.P. 32,172 135,000 0.03%
113 PROFUND ADVISORS LLC 31,737 134,000 0.03%
114 Index Management Solutions, LLC 30,128 127,000 0.03%
115 GROUP ONE TRADING LLC 29,987 126,000 0.03%
116 Municipal Employees' Retirement System of Michigan 29,700 125,000 0.03%
117 Cambridge Investment Research Advisors, Inc. 29,270 123,000 0.03%
118 STEVENS CAPITAL MANAGEMENT LP 28,441 120,000 0.03%
119 CSS LLC/IL 28,400 120,000 0.03%
120 KMS FINANCIAL SERVICES, INC 26,610 112,000 0.03%
121 TRUST CO OF TOLEDO NA /OH/ 25,175 106,000 0.02%
122 BANK OF MONTREAL /CAN/ 24,718 104,000 0.02%
123 TUDOR INVESTMENT CORP ET AL 22,009 93,000 0.02%
124 Princeton Alpha Management LP 21,827 92,000 0.02%
125 UBS AG 20,192 85,000 0.02%
126 MANNING & NAPIER ADVISORS LLC 20,260 85,000 0.02%
127 PUBLIC EMPLOYEES RETIREMENT SYSTEM OF OHIO 19,219 81,000 0.02%
128 COMMERZBANK AKTIENGESELLSCHAFT /FI 16,823 71,000 0.02%
129 BARCLAYS PLC 16,700 67,000 0.02% Put
130 MASON STREET ADVISORS, LLC 15,595 66,000 0.01%
131 SG Americas Securities, LLC 14,662 62,000 0.01%
132 Spot Trading L.L.C 14,600 61,000 0.01% Call
133 MENTA CAPITAL LLC 13,500 57,000 0.01%
134 Tradeworx Inc. 13,060 55,000 0.01%
135 CIBC Asset Management Inc 12,477 53,000 0.01%
136 BOKF, NA 12,270 51,000 0.01%
137 Ameritas Investment Partners, Inc. 11,881 50,000 0.01%
138 SEGALL BRYANT & HAMILL, LLC 11,880 50,000 0.01%
139 Mraz, Amerine & Associates, Inc. 11,900 50,000 0.01%
140 SHELTON CAPITAL MANAGEMENT 11,605 49,000 0.01%
141 World Asset Management Inc 11,311 48,000 0.01%
142 SUNTRUST BANKS INC 11,401 47,000 0.01%
143 Nuveen Asset Management, LLC 11,098 47,000 0.01%
144 PEAK6 Group LLC 10,687 45,000 0.01%
145 HBK INVESTMENTS L P 10,054 42,000 0.01%
146 B. Riley Wealth Advisors, Inc. 10,000 42,000 0.01%
147 Twin Tree Management, LP 10,000 42,000 0.01% Call
148 PRELUDE CAPITAL MANAGEMENT, LLC 9,300 39,000 0.01%
149 PEAK6 Group LLC 7,900 33,000 0.01% Put
150 UBS AG 6,500 27,000 0.01% Put
Page 3 of 4

From 2023-01-03 onward, the SEC requires values to be reported in nearest dollars. Earlier filings reported values in thousands; therefore, positions shown as $0 in older filings may represent actual values between $0–$999.