After defying gravity for the past couple of years, Palantir Technologies ( PLTR -5.17%) has finally hit turbulence, with the stock plunging as much as 14.9% on Thursday. As of 11:27 a.m. ET, the stock was still down 11.4%.

The big-data analytics company’s latest rally has lifted its valuation to 75 times the $3.75 billion in sales that analysts forecast for this year.

Move aside Apple, Microsoft, Alphabet and Tesla. There's a new group of Magnificent Seven stocks in the S&P 500.

One of the country's largest pension funds has taken a stake in the artificial intelligence (AI) and data mining specialist.