ION GEOPHYSICAL CORP

CUSIP: 462044108 Class: COM

DIMENSIONAL FUND ADVISORS LP's Holding History (CIK: 0000354204)

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

Q4 2015
Shares 4,193,744 Value ($000) $2,110 Avg Close — Range —
Q3 2015
Shares 4,313,567 Value ($000) $1,682 Avg Close — Range —
Q2 2015
Shares 4,529,738 Value ($000) $4,847 Avg Close — Range —
Q1 2015
Shares 4,728,434 Value ($000) $10,261 Avg Close — Range —
Q4 2014
Shares 4,710,949 Value ($000) $12,955 Avg Close — Range —
Q3 2014
Shares 4,654,858 Value ($000) $12,988 Avg Close — Range —
Q2 2014
Shares 4,331,262 Value ($000) $18,278 Avg Close — Range —
Q1 2014
Shares 3,588,307 Value ($000) $15,106 Avg Close — Range —
Q4 2013
Shares 3,648,093 Value ($000) $12,038 Avg Close — Range —
Q3 2013
Shares 3,647,008 Value ($000) $18,964 Avg Close — Range —
Q2 2013
Shares 3,694,903 Value ($000) $22,243 Avg Close — Range —