The S&P 500 is set for a small gain for the month, despite a slide in some of the tech stocks that led the index to repeated new highs.

Amazon on Thursday became the latest tech company to announce swelling investments in A.I. amid stumbling share prices.

© Nathan Howard for The New York Times

A.I. has uncovered a horde of software flaws, which engineers are racing to fix before they can be exploited and abused by hackers.

© Ariel Davis