A slang term for a decline in the overall value of the stock market. Market swoons can be seen when indexes, such as the Dow Jones Industrial Average (DJIA) , have a significant drop in price. Taobiz explains Market Swoon Market swoons are often caused by the negative sentiment of investors. When investors grow nervous or fear an upcoming economic event, they will usually stop trading or liquidate a position. This will cause a swoon, lowering security prices across the market.