American Axle & Manufacturing (AXL) had the highest return in May 2009 by a small-cap US stock, returning 100%.

ASSET	MONTH	% RETURN
American Axle & Manufacturing (AXL)	May 2009	100%
Talos Energy (TALO)	May 2009	98.86%
Federal Agricultural Mortgage (AGM)	May 2009	97.79%
Canadian Solar (CSIQ)	May 2009	97.17%
AtriCure (ATRC)	May 2009	92.06%
Photronics (PLAB)	May 2009	89.22%
Federal Agricultural Mortgage (AGM.A)	May 2009	88.89%
Niagen Bioscience (NAGE)	May 2009	85.71%
Green Plains Renewable Energy (GPRE)	May 2009	82.58%
ODP (ODP)	May 2009	81.32%
Safe Bulkers (SB)	May 2009	78.8%
North American Construction (NOA)	May 2009	72.32%
BioLife Solutions (BLFS)	May 2009	66.67%
Ultra Clean (UCTT)	May 2009	62.78%
MannKind (MNKD)	May 2009	60.1%
ADEIA (ADEA)	May 2009	59.4%
Sify Technologies (SIFY)	May 2009	58.47%
Lendingtree (TREE)	May 2009	58.4%
Tetra Technologies (TTI)	May 2009	56.2%
Andersons (ANDE)	May 2009	56.19%
Sinclair Broadcast (SBGI)	May 2009	55.77%
Idaho Strategic Resources (IDR)	May 2009	55.56%
Verint Systems (VRNT)	May 2009	53.51%
Clearwater Paper (CLW)	May 2009	52.71%
Mitek Systems (MITK)	May 2009	52.17%

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