Pinpoint Portfolio: Why Markets Are Manic Right Now

Investors keep changing their minds about AI winners and losers. Here's why.

Microsoft made history on July 30 when it registered the largest one-day gain in market value ever. The stock jumped from $391 per share to $451, which increased the company’s value by $450 billion, to $3.4 trillion.

Is that a good thing? Probably not. Huge swings in stock prices are a mark of volatility, and certain corners of the stock market are pretty manic right now, as investors try to identify the winners and losers of the artificial-intelligence revolution.

[Pop quiz: What the biggest one-day loss of market value? Answer at the bottom.]

That narrative keeps changing, with some stocks and sectors going in and out of favor. Microsoft is a good case study in investor fickleness.