Green Brick Partners (GRBK) had the best month in 2011 by a mid-cap US stock in October 2011, returning 155%.

ASSET	MONTH	% RETURN
Green Brick Partners (GRBK)	October 2011	155.02%
Applied Blockchain (APLD)	August 2011	110.53%
QXO (QXO)	April 2011	100%
Plug Power (PLUG)	January 2011	97.63%
Globalstar (GSAT)	October 2011	76.62%
United Community Banks (UCB)	March 2011	70.07%
Option Care Health (OPCH)	May 2011	64.87%
Terex (TEX)	October 2011	63.94%
IPG Photonics (IPGP)	February 2011	61.89%
Greenbrier Companies (GBX)	October 2011	61.83%
Applied Blockchain (APLD)	April 2011	60%
QXO (QXO)	October 2011	60%
Catalyst Pharmaceuticals (CPRX)	June 2011	59.32%
ACADIA Pharmaceuticals (ACAD)	April 2011	58.05%
TG Therapeutics (TGTX)	January 2011	57.89%
Universal Display (OLED)	August 2011	55.7%
ASGN (ASGN)	October 2011	54.45%
Talos Energy (TALO)	October 2011	52.22%
Denison Mines (DNN)	October 2011	51.95%
Patrick Industries (PATK)	December 2011	51.86%
Melco Resorts & Entertainment (MLCO)	October 2011	48.19%
Avis Budget (CAR)	October 2011	47.95%
InterDigital (IDCC)	July 2011	46.59%
Riot Blockchain (RIOT)	March 2011	45.3%
Vera Therapeutics (VERA)	December 2011	44.71%

Mid-cap stocks are treated as having a market cap between $2B and $10B.