Comstock Resources (CRK) had the highest return in October 1987 by a US stock, returning 50%.

ASSET	MONTH	% RETURN
Comstock Resources (CRK)	October 1987	50%
Citizens (CIA)	October 1987	46.67%
Donegal Group B (DGICB)	October 1987	8.34%
CVB Financial (CVBF)	October 1987	7.33%
Duke Energy (DUK)	October 1987	4.63%
Avangrid (AGR)	October 1987	2.53%
Weyco (WEYS)	October 1987	2.27%
TXNM Energy (TXNM)	October 1987	2.05%
Intergroup (INTG)	October 1987	2%
SRH Total Return Fund (STEW)	October 1987	1.39%
Dominion Energy (D)	October 1987	1.2%
American Vanguard (AVD)	October 1987	0%
Central Pacific Financial (CPF)	October 1987	0%
Soligenix (SNGX)	October 1987	0%
First Financial Bancorp (FFBC)	October 1987	0%
CVD Equipment (CVV)	October 1987	0%
Acco Brands (ACCO)	October 1987	0%
GT Biopharma (GTBP)	October 1987	0%
InnSuites Hospitality Trust (IHT)	October 1987	0%
Range Resources (RRC)	October 1987	0%
Abeona Therapeutics (ABEO)	October 1987	0%
WEC Energy (WEC)	October 1987	-0.51%
OGE Energy (OGE)	October 1987	-1.11%
Icahn Enterprises (IEP)	October 1987	-1.57%
American Electric Power (AEP)	October 1987	-1.81%