Correlation matrix

Banks: daily returns, last 250 sessions

	Maybank	CIMB	Public Bank	RHB Bank	AMMB	HL Bank	Alliance Bank	Bank Islam	Affin Bank
Maybank		0.51	0.51	0.47	0.44	0.42	0.42	0.34	0.34
CIMB	0.51		0.55	0.42	0.55	0.51	0.50	0.32	0.33
Public Bank	0.51	0.55		0.40	0.47	0.50	0.47	0.18	0.41
RHB Bank	0.47	0.42	0.40		0.52	0.48	0.40	0.20	0.35
AMMB	0.44	0.55	0.47	0.52		0.38	0.45	0.17	0.31
HL Bank	0.42	0.51	0.50	0.48	0.38		0.39	0.26	0.38
Alliance Bank	0.42	0.50	0.47	0.40	0.45	0.39		0.26	0.40
Bank Islam	0.34	0.32	0.18	0.20	0.17	0.26	0.26		0.29
Affin Bank	0.34	0.33	0.41	0.35	0.31	0.38	0.40	0.29

1.00 means two stocks moved in lockstep, 0 means no relationship, and negative values mean they tended to move in opposite directions. Holding highly correlated stocks gives less diversification than it looks.