American Airlines (AAL) had the highest return in August 2008 by a large-cap US stock, returning 60.2%.

ASSET	MONTH	% RETURN
American Airlines (AAL)	August 2008	60.19%
Advanced Micro Devices (AMD)	August 2008	47.65%
Cheniere Energy Partners (CQP)	August 2008	31.68%
Align Technology (ALGN)	August 2008	31.19%
Dick’s Sporting Goods (DKS)	August 2008	30.13%
Axon Enterprise (AXON)	August 2008	28.97%
Ralph Lauren Corp Class A (RL)	August 2008	28.44%
Live Nation Entertainment (LYV)	August 2008	27.08%
Super Micro Computer (SMCI)	August 2008	25.41%
United Airlines (UAL)	August 2008	24.97%
ResMed (RMD)	August 2008	24.27%
Cheniere Energy (LNG)	August 2008	23.28%
Toll Brothers (TOL)	August 2008	22.5%
Coca-Cola Consolidated (COKE)	August 2008	20.93%
Lowe's Companies (LOW)	August 2008	20.55%
Monster Beverage (MNST)	August 2008	20.22%
American Water Works (AWK)	August 2008	19.5%
Keurig Dr Pepper (KDP)	August 2008	18.86%
F5 Networks (FFIV)	August 2008	18.03%
Nasdaq (NDAQ)	August 2008	17.59%
Masco (MAS)	August 2008	17.29%
Caseys General Stores (CASY)	August 2008	17.27%
PulteGroup (PHM)	August 2008	17.02%
STMicroelectronics NV ADR (STM)	August 2008	16.93%
Target (TGT)	August 2008	16.84%

Large-cap stocks are treated as having a market cap of $10B+.