Draw the graph - Actual, Theory and Residual.

plot(merge(merge(apply.quarterly(SP5[k2k],mean)[,1],predict(lm(apply.quarterly(SP5[k2k],mean)[,1] ~ PAq[k2k] * UCq[k2k] * G[k2k]*CSq[k2k] - UCq[k2k] -G[k2k] - PAq[k2k]*G[k2k] - UCq[k2k]*G[k2k]*CSq[k2k]))),
+ residuals(lm(apply.quarterly(SP5[k2k],mean)[,1] ~ PAq[k2k] * UCq[k2k] * G[k2k]*CSq[k2k] - UCq[k2k] -G[k2k] - PAq[k2k]*G[k2k] - UCq[k2k]*G[k2k]*CSq[k2k]))))
axis(2,at=c(100,50,0,-50,-100,-150))
axis(4,at=c(100,50,0,-50,-100,-150))

black = actual
red = theory
green = residual

# or draw horizontal line at the designated x-value, please not that
# the index must be synchronized with the main graph, which is equal to
#  seq(as.Date("2000-03-01"),as.Date("2017-12-01"),by='quarters'))
# no to k2k.

plot(merge(merge(apply.quarterly(SP5[k2k],mean)[,1],predict(lm(apply.quarterly(SP5[k2k],mean)[,1] ~ PAq[k2k] * UCq[k2k] * G[k2k]*CSq[k2k] - UCq[k2k] -G[k2k] - PAq[k2k]*G[k2k] - UCq[k2k]*G[k2k]*CSq[k2k]))),
+            + residuals(lm(apply.quarterly(SP5[k2k],mean)[,1] ~ PAq[k2k] * UCq[k2k] * G[k2k]*CSq[k2k] - UCq[k2k] -G[k2k] - PAq[k2k]*G[k2k] - UCq[k2k]*G[k2k]*CSq[k2k]))),ylim=c(-200,3000))
# addSeries(as.xts(rep(-100,72),index(apply.quarterly(SP5[k2k],mean)[,1])),on=1,ylim=c(-200,2700),lwd=1)
addSeries(as.xts(rep(-100,length(index(apply.quarterly(SP5[k2k],mean)[,1]))),index(apply.quarterly(SP5[k2k],mean)[,1])),on=1,ylim=c(-200,3000),lwd=1)