Altimmune (ALT) had the highest return in August 2014 by a small-cap US stock, returning 74.8%.

ASSET	MONTH	% RETURN
Altimmune (ALT)	August 2014	74.81%
InnovAge (INNV)	August 2014	65%
Arbutus Biopharma (ABUS)	August 2014	62.12%
Digital Turbine (APPS)	August 2014	53.95%
MGP Ingredients (MGPI)	August 2014	48.63%
Cadiz (CDZI)	August 2014	47.71%
Canadian Solar (CSIQ)	August 2014	45.19%
Crossamerica Partners (CAPL)	August 2014	42.55%
Willdan (WLDN)	August 2014	41.63%
Daqo New Energy Corp ADR (DQ)	August 2014	38.44%
Amphastar P (AMPH)	August 2014	36.76%
Allient (ALNT)	August 2014	34.9%
American Woodmark (AMWD)	August 2014	33.04%
Vaalco Energy (EGY)	August 2014	32.61%
Prothena (PRTA)	August 2014	31.23%
Star Bulk Carriers (SBLK)	August 2014	30.61%
CTO Realty Growth (CTO)	August 2014	30.52%
Red Cat (RCAT)	August 2014	29.63%
Himax Technologies (HIMX)	August 2014	29.19%
Pacific Biosciences of California (PACB)	August 2014	28.79%
Xpel (XPEL)	August 2014	28.61%
Nektar Therapeutics (NKTR)	August 2014	28.35%
Insteel Industries (IIIN)	August 2014	27.54%
Andersons (ANDE)	August 2014	26.95%
REX American Resources (REX)	August 2014	26.67%

Small-cap stocks are treated as having a market cap between $300M and $2B.