Theoretically, a market crash without subsequent government policy to negate the effects can cause deflation.

Remember that deflation means lower prices, less demand for stuff, and a market crash would do exactly this, lower prices for shares for once and fewer returns as companies try to consolidate or avoid bankruptcies, an exodus of money into more secure stuff triggering further sellout, and poeple far less inclined to spend money on goods. The great depression is the perfect example, we had a market crash, assets were liquidated by cash-strapped companies, nobody had to buy them, ending with an average of 7% decline per year in prices.


So if a tesla share drops from 1000$ to 100$, how is that inflation?
If the housing bubble pops and houses go on fire sale for 1/4 of the price what do you call that?
Remember that the EU went into deflation both in 2009 and 2015.