F5 Networks (FFIV) had the highest return in October 1999 by a large-cap US stock, returning 107.1%.

ASSET	MONTH	% RETURN
F5 Networks (FFIV)	October 1999	107.09%
MicroStrategy (MSTR)	October 1999	70.08%
Trimble (TRMB)	October 1999	52.93%
Cognizant Technology Solutions Corp Class A (CTSH)	October 1999	43.55%
PTC (PTC)	October 1999	41.2%
Check Point Software Technologies (CHKP)	October 1999	39.38%
Lam Research (LRCX)	October 1999	39.28%
Telefonaktiebolaget LM Ericsson B ADR (ERIC)	October 1999	37.63%
Fair Isaac (FICO)	October 1999	37.33%
Capital One Financial (COF)	October 1999	36.55%
Genesis Healthcare (GEN)	October 1999	33.57%
Suzano Papel e Celulose SA ADR (SUZ)	October 1999	32.27%
Akamai Technologies (AKAM)	October 1999	31.99%
Colgate-Palmolive (CL)	October 1999	31.88%
Hartford Financial Services (HIG)	October 1999	30.35%
Apple (AAPL)	October 1999	28.98%
Telkom Indonesia (Persero) Tbk PT ADR Rep 100 B (TLK)	October 1999	28.95%
Nokia (NOK)	October 1999	28.94%
Reinsurance Group of America (RGA)	October 1999	28.81%
Microchip Technology (MCHP)	October 1999	28.59%
T Rowe Price (TROW)	October 1999	28.22%
Bank of New York Mellon (BK)	October 1999	27.39%
Citigroup (C)	October 1999	26.53%
Copart (CPRT)	October 1999	26.32%
Bio-Techne (TECH)	October 1999	26%

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