I am neck deep in the federal election, hence my very infrequent writing in April.
With the surge of the NDP in Canada, there is a distinct possibility that the NDP will be a very significant partner in any coalition government against the Conservatives. Economically, one of the promises all the other parties have had is an increase in the corporate tax rate. In particular, banks and oil companies have been singled out by the NDP. Whether they would take action upon them in government or not is another matter, but the corporate tax rate increase is something they would likely implement.
In terms of making a trade based on the projection of the election, I would suspect that selling/shorting profitable large-cap companies on the TSX would be the best way of betting against a Conservative majority government. You would close the position on May 3rd.
In the event that the Conservatives are quite short of a majority government (e.g. a status quo situation), there is likely going to be a few months of major uncertainty before the House of Commons sits for its throne speech. Although the writs are going to be returned sometime in the later part of May, the Prime Minister has the option of not convening Parliament until after the summer break, in September. This is probable if there is another minority government.
This uncertainty only leads in one direction – equity price decreases in Canada.