They don't always all line up in time. Companies grow and die all the time. Trends, Hypes and Bubbles are probably a consequence of human nature: most investor

They don't always all line up in time. Companies grow and die all the time. Trends, Hypes and Bubbles are probably a consequence of human nature: most investors have a deep fear-of-missing out, so in general money loves to jump on the hype-train. Likewise, fear and uncertainty easily spread: markets moving together. When a couple of businesses fail, that insolvency or illiquidity spreads to related businesses.