ION GEOPHYSICAL CORP

CUSIP: 462044108 Class: COM

GROUP ONE TRADING, L.P.'s Holding History (CIK: 0000932540)

Note: Option positions (PUT/CALL) are excluded.

Q1 2015
Shares 1,512 Value ($000) $3 Avg Close — Range —
Q4 2014
Shares 1,412 Value ($000) $4 Avg Close — Range —
Q1 2014
Shares 29,987 Value ($000) $126 Avg Close — Range —
Q4 2013
Shares 9,087 Value ($000) $30 Avg Close — Range —
Q3 2013
Shares 7,787 Value ($000) $40 Avg Close — Range —