Business, and political fads, have always run in cycles. there is a book out a while back called The Great Wave, iirc, that discusses several of them over many centuries, and the cumulative effects of what happened when some of them all decides to tank at the same time. There are lots of odd factoids about the stock markets, don't know if they're just coincidental to exact years, though, but the cyclic patterns are more or less there, at least going by past data. Predicting them is another story; even the great economist Maynard Keynes lost his ass in the stock market making a bad guess. What he thought was going to happen did indeed happen, his timing just sucked. Despite all the hate and idiotic propaganda directed at him, he was an excellent fund manager for his university when making conservative investment decisions, and regularly got 12% + returns for the uni's trust fund, even in Depression years. It's just trendy to pretend he was some sort of commie and incompetent loser with some of the wingtards, most of whom don't know squat themselves, is all.
Imho, the 'market' is heavily over-capitalized and the economy too concentrated for the stock markets to be reflections of the real economy, and that concentration trend has been on steriods since the crash. Only a tiny handful of companies cause big movements in stock prices, and too much cash is concentrated at the top of the pyramid. The recent frenzy over the Bit Coin Ponzi scheme is just another manifestation of the real lack of productive investment outlets for surplus cash. I do thank all the tards who jumped into that idiocy for driving up the value of my gold hedges, though, a windfall I wasn't expecting, and thanks for the new truck I bought with some of it.