ION GEOPHYSICAL CORP

CUSIP: 462044108 Class: COM

PRINCIPAL FINANCIAL GROUP INC's Holding History (CIK: 0001126328)

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

Q4 2015
Shares 20,364 Value ($000) $10 Avg Close — Range —
Q3 2015
Shares 831,407 Value ($000) $324 Avg Close — Range —
Q2 2015
Shares 782,499 Value ($000) $837 Avg Close — Range —
Q1 2015
Shares 831,489 Value ($000) $1,805 Avg Close — Range —
Q4 2014
Shares 809,157 Value ($000) $2,225 Avg Close — Range —
Q3 2014
Shares 806,420 Value ($000) $2,249 Avg Close — Range —
Q2 2014
Shares 779,024 Value ($000) $3,287 Avg Close — Range —
Q1 2014
Shares 774,236 Value ($000) $3,260 Avg Close — Range —
Q4 2013
Shares 774,090 Value ($000) $2,554 Avg Close — Range —
Q3 2013
Shares 713,536 Value ($000) $3,710 Avg Close — Range —
Q2 2013
Shares 2,141,276 Value ($000) $12,890 Avg Close — Range —