Second Act for Corporate Titans: Startup Whisperers

Cisco’s John Chambers and AmEx’s Kenneth Chenault are part of a wave of former big-name executives who are putting their business acumen to work in venture capital and offering counsel to young companies

In his two decades running Cisco Systems Inc., John Chambers transformed what was a small networking-equipment company into a tech giant. His second act? Investing in and coaching more than a dozen startups with the hope of creating the next Cisco.

After retiring as Cisco’s executive chairman last year (he stepped down as chief executive in 2015), the 68-year-old Silicon Valley pioneer launched a venture-capital fund, JC2 Ventures, with $100 million of his own money. But it’s not just his money at work. To the fledgling companies...