NATURAL GAS SERVICES GROUP

Ticker: NGS CUSIP: 63886Q109 Class: Common Stock

Walleye Trading LLC's Holding History (CIK: 0001388391)

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

Q4 2016

Shares 1,100 Value ($000) $35 Avg Close $27.19 Range $20.43 - $34.13

Q2 2016

Shares 1,600 Value ($000) $37 Avg Close $22.14 Range $19.61 - $25.27

Q3 2015

Shares 600 Value ($000) $12 Avg Close $20.31 Range $18.37 - $22.64

Period	Shares	Value ($000)	Average Close	Price Range
Q4 2016	1,100	$35	$27.19	$20.43 - $34.13
Q2 2016	1,600	$37	$22.14	$19.61 - $25.27
Q3 2015	600	$12	$20.31	$18.37 - $22.64