How Come Volatility Is So Darn Wild?

Lots of bad news is one reason. But changes in the market’s structure figure in, too.

“I feel the need—the need for speed!” So says Tom Cruise’s fighter pilot character, Pete “Maverick” Mitchell, in the 1986 blockbuster “Top Gun,” expressing a kinetic impulse he shows yet again in the sequel out this past Memorial Day weekend. The stock market feels that same need, and in dollar terms share trading is many times more popular than Maverick’s box office.