The following chart plots the number of times the FTSE All-Share Index has had positive returns in the 7 days around UK parliamentary elections since 1970.

For example, in the 12 elections there have been since 1970 the Index has risen 7 times on the third day, E(-3), before election day E(0).

The following chart is similar to the above but plots the average day returns for the Index on each of the 7 days around elections.

For example, in the 12 elections since 1970 the Index has had an average return of 0.1% on the day before, E(-1), the election.

Interestingly, the market  has tended to see positive returns in the days immediately around elections, with the strongest day being election day itself with an average return of 0.6% (perhaps a .relief rally marking the end of the tedious election campaigns?)

The day following elections has a negative average return of  0.04% (as investors realise the ramifications of the election result?)

Further articles on the market and elections.