What are the risks of putting money in the stock market that I'm intending to use 6 months from now for the downpayment on a house?

There are two things that people generally forget when investing in the stock market: only invest what you can afford to lose and the objective of trading is to protect your capital (the latter is critical advice for novice traders).

Putting your down payment on a house is not advisable.

Even taking the down payment factor out of the equation, the financial market either in the U.S. or Canada could experience a steep correction based on these elements:

Federal Reserve or Bank of Canada would raise interest rates and taper monetary support and stimulus tools.

Inflation could force investors into bonds, especially if central banks pull the trigger on a rate hike.

The VIX is beginning to indicate that trouble is brewing in the equities arena.

Nearly everything is trading at all-time highs, so it is difficult to foresee any new entrant replicating those gains as we have witnessed over the last 15 months.

If you need to invest this down payment, you are better off relying on an index fund that pays a dividend.