Amazon (AMZN) had the highest return between 1994 and 1998 by a mega-cap US stock, returning 2,096.1%.

ASSET	YEARS	% RETURN
Amazon (AMZN)	1994-1998	2,096.14%
Microsoft (MSFT)	1994-1998	1,278.26%
Cisco Systems (CSCO)	1994-1998	1,195.05%
Intel (INTC)	1994-1998	670.12%
International Business Machines (IBM)	1994-1998	584.42%
Eli Lilly and (LLY)	1994-1998	581.11%
Texas Instruments (TXN)	1994-1998	467.67%
Micron Technology (MU)	1994-1998	450.11%
ASML Holding NV New York Registry Shares (ASML)	1994-1998	442.23%
Oracle (ORCL)	1994-1998	406.24%
Merck (MRK)	1994-1998	376.64%
Home Depot (HD)	1994-1998	373.68%
Morgan Stanley (MS)	1994-1998	342.46%
Applied Materials (AMAT)	1994-1998	340.64%
GE Aerospace (GE)	1994-1998	335.53%
JPMorgan Chase (JPM)	1994-1998	330.69%
Berkshire Hathaway (BRK.A)	1994-1998	327.48%
American Express (AXP)	1994-1998	325.37%
Amgen (AMGN)	1994-1998	324.61%
Johnson & Johnson (JNJ)	1994-1998	308.2%
RTX (RTX)	1994-1998	294.04%
Costco Wholesale (COST)	1994-1998	277.45%
Wells Fargo (WFC)	1994-1998	276.13%
Procter & Gamble (PG)	1994-1998	251.82%
Gilead Sciences (GILD)	1994-1998	242.24%

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