American Express (AXP) had the highest return in April 2009 by a mega-cap US stock, returning 89.1%.

ASSET	MONTH	% RETURN
American Express (AXP)	April 2009	89.06%
Wells Fargo (WFC)	April 2009	45.85%
Bank of America (BAC)	April 2009	38.45%
Blackstone (BX)	April 2009	37.7%
Salesforce (CRM)	April 2009	36.95%
JPMorgan Chase (JPM)	April 2009	30.72%
GE Aerospace (GE)	April 2009	27.65%
Royal Bank of Canada (RY)	April 2009	25.14%
Goldman Sachs (GS)	April 2009	23.44%
ASML Holding NV ADR (ASML)	April 2009	23.18%
Walt Disney (DIS)	April 2009	22.21%
HSBC Holdings PLC ADR (HSBC)	April 2009	21.17%
Advanced Micro Devices (AMD)	April 2009	21.14%
Apple (AAPL)	April 2009	20.88%
Toyota Motor Corporation ADR (TM)	April 2009	19.63%
Visa Inc Class A (V)	April 2009	18.65%
Taiwan Semiconductor Manufacturing (TSM)	April 2009	18.5%
NVIDIA (NVDA)	April 2009	17.92%
Cisco Systems (CSCO)	April 2009	17.02%
Alphabet Inc Class A (GOOGL)	April 2009	15.18%
Raytheon Technologies (RTX)	April 2009	15.05%
UnitedHealth (UNH)	April 2009	14.12%
Home Depot (HD)	April 2009	13.69%
LIN TV (LIN)	April 2009	12.75%
Mastercard (MA)	April 2009	12.38%

Mega-cap stocks are treated as having a market cap of $200B+.