Acme Packet Inc. (Nasdaq:APKT), TranS1 Inc. (Nasdaq:TSON) and ARYx Therapeutics Inc. (Nasdaq:ARYX) are among the biggest percentage losers in Thursday's trading among companies with market capitalizations under $1 billion.

Also included among the results: Pyramid Oil Company (AMEX:PDO), Gushan Environmental Energy Limited (NYSE:GU), Security Bank Corp. (Nasdaq:SBKC), ChemGenex Pharmaceuticals Limited (Nasdaq:CXSP), Volterra Semiconductor Corp. (Nasdaq:VLTR) and Fuel Systems Solutions Inc. (Nasdaq:FSYS).

Here are the biggest percentage losers among small caps:

		Price at 11:47 ET	Change	% Change	Volume	Year High	Year Low
APKT	ACME PACKET INC	5.24	-2.54	-32.6%	773.3k	16.59	6.85
TSON	TRANS1 INC	10.05	-4.20	-29.5%	551.5k	26.48	8.61
ARYX	ARYX THERAPEUTICS INC	5.02	-1.55	-23.6%	13.3k	9.74	3.71
PDO	PYRAMID OIL CO	23.68	-4.32	-15.4%	477.8k	46.00	2.19
GU	GUSHAN ENVIRONMENTAL ENRGY L	10.50	-1.73	-14.1%	1,384.7k	17.95	7.00
SBKC	SECURITY BANK CORP	5.54	-0.82	-12.9%	67.2k	20.02	2.67
CXSP	CHEMGENEX PHARMACEUTICALS LT	20.94	-2.56	-10.9%	3.3k	26.99	8.58
VLTR	VOLTERRA SEMICONDUCTOR CORP	15.37	-1.80	-10.5%	1,065.1k	17.77	7.79
FSYS	FUEL SYS SOLUTIONS INC	28.92	-3.14	-9.8%	573.1k	41.90	9.80
EGY	VAALCO ENERGY INC	7.49	-0.76	-9.2%	755.8k	8.98	3.62