By 10.11am on Thursday morning, Telstra's army of investors had collectively torched $28.5 billion under Andy Penn's leadership. Is it time to look for a new leader?

The value destruction has been enormous, and yes Telstra's future on a margin-shredding NBN network is partly to blame, but only partly.

The reign of Penn, which began in May 2015, has not been a happy one for investors.

Sure, former CEO David Thodey openly admitted that he had a strong tailwind from the hard work done under his controversial predecessor, Sol Trujillo.