One such shareholder was David Hoeft, a member of the Dodge & Cox committee that made the decision to buy the shares and an advocate for investing in technology companies. Hoeft, who has spent 30 years at Dodge & Cox, is now the company’s chief investment officer.

For decades, regulators have tried to clamp down on front-running, the term for when investment professionals make personal purchases or sales of securities when they know that their employers or clients are about to buy or sell the same securities. But a massive assemblage of confidential stock trading data obtained by ProPublica reveals that the practice may be continuing on a notable scale.

Hoeft is one of dozens of investment managers at hedge funds and mutual funds who personally traded the same securities that their organizations were buying and selling, ProPublica found. He stood out in this group for the volume and fortuitous timing of such trades. From 2011 to 2019, Hoeft traded stocks on at least 31 days in the same quarter or the quarter before Dodge & Cox traded the same securities. The transactions were worth nearly $50 million. (All told, Hoeft’s personal trades, most of them in stocks his employer was not trading, totalled more than $725 million during the period.)