Wall Street economists are oblivious to record trade deficits that in any other age would chop the value of the offending nation's currency to a fraction of its former purchasing power. Derivatives are subject to an accident. There are approximately one hundred trillion dollars in derivatives. It's not impossible in a crisis for cascading numbers of derivative problems to unfold. Rising interest rates.
Interest rates impact heavily the profits of publicly-held corporations.
They also raise the cost of borrowing to invest. High rates historically choke off speculation. Investors erroneously believe they can get out of the market ahead of any major downturn. It's taken almost 20 years for investors to pour this much money into the stock market. If they should head for the exit in a panic or disorder, there is no way for the majority to get out smoothly.