Monster Beverage (MNST) had the highest return in April 1998 by a US stock in the S&P 500 (GSPC), returning 37%.

ASSET	MONTH	% RETURN
Monster Beverage (MNST)	April 1998	36.96%
Tyler Technologies (TYL)	April 1998	35.2%
Microchip Technology (MCHP)	April 1998	32.74%
United Rentals (URI)	April 1998	32.45%
Synopsys (SNPS)	April 1998	31.8%
Laboratory Corporation of America (LH)	April 1998	29.03%
Regeneron Pharmaceuticals (REGN)	April 1998	28.69%
Fastenal (FAST)	April 1998	27.67%
Copart (CPRT)	April 1998	23.53%
IDEXX Laboratories (IDXX)	April 1998	22.35%
McKesson (MCK)	April 1998	22.27%
Tractor Supply (TSCO)	April 1998	21.18%
HP (HPQ)	April 1998	18.94%
Texas Instruments (TXN)	April 1998	18.64%
Ball (BALL)	April 1998	17.94%
Viatris (VTRS)	April 1998	17.94%
Caesars Entertainment (CZR)	April 1998	17.89%
Walt Disney (DIS)	April 1998	16.86%
Analog Devices (ADI)	April 1998	16.23%
Capital One Financial (COF)	April 1998	16.09%
Eli Lilly and (LLY)	April 1998	15.94%
Skyworks Solutions (SWKS)	April 1998	14.17%
Quest Diagnostics (DGX)	April 1998	14.07%
Pfizer (PFE)	April 1998	13.81%
Western Digital (WDC)	April 1998	12.86%