Slack CEO Is $400 Million Richer From Salesforce Deal Talks (1)

Stewart Butterfield is already benefitting from Salesforce.com Inc.’s potential acquisition of Slack Technologies Inc.

The fortune of Slack’s billionaire co-founder and chief executive officer increased about $400 million from reports this week that Salesforce is considering taking over the workplace chat tool.

Stewart Butterfield

Photographer: David Paul Morris/Bloomberg

Slack shares were down 3.2% to $39.39 at 9:38 a.m. Friday after surging 38% on Wednesday, the most since the first day of trading last year following a direct listing onto the New York Stock Exchange. Butterfield’s stake in Slack is worth about $1.6 billion, according to the Bloomberg Billionaires Index.

If a deal happens, ...