A new wave of S&P 500 companies is making sure employees know they can’t use information gained on the job to place bets on online prediction markets.

FedEx Corp., PepsiCo Inc., and sports company TKO Group Holdings Inc. this week joined a smattering of other major companies — including JPMorgan Chase & Co., Dominion Energy Inc., KeyCorp, Altria Group Inc., and Cisco Systems Inc. — that have in the past month disclosed updates to their internal codes of conduct or insider trading policies that account for activities on the platforms, according to Bloomberg Terminal data.

“FedEx expects all …