Cisco Systems (CSCO) had the highest return between 1994 and 2000 by a mega-cap US stock, returning 2,034.8%.

ASSET	YEARS	% RETURN
Cisco Systems (CSCO)	1994-2000	2,034.83%
Oracle (ORCL)	1994-2000	1,947.03%
ASML Holding NV ADR (ASML)	1994-2000	1,103.32%
Morgan Stanley (MS)	1994-2000	963.36%
Microsoft (MSFT)	1994-2000	762.07%
Applied Materials (AMAT)	1994-2000	688.39%
Intel (INTC)	1994-2000	683.32%
Micron Technology (MU)	1994-2000	672.58%
Eli Lilly and (LLY)	1994-2000	632.2%
American Express (AXP)	1994-2000	597.21%
Amazon (AMZN)	1994-2000	538.31%
International Business Machines (IBM)	1994-2000	536.99%
GE Aerospace (GE)	1994-2000	528.57%
Merck (MRK)	1994-2000	525.09%
Raytheon Technologies (RTX)	1994-2000	485.11%
Wells Fargo (WFC)	1994-2000	446.23%
Home Depot (HD)	1994-2000	433.75%
Johnson & Johnson (JNJ)	1994-2000	424.54%
Walmart Inc Common Stock (WMT)	1994-2000	337.9%
Berkshire Hathaway (BRK.A)	1994-2000	333.59%
JPMorgan Chase (JPM)	1994-2000	332.51%
Costco Wholesale (COST)	1994-2000	317.65%
Royal Bank of Canada (RY)	1994-2000	243.52%
UnitedHealth (UNH)	1994-2000	225.92%
NVIDIA (NVDA)	1994-2000	211.97%

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