A smart guy with big shoes to fill is probably the most apt description of Mike Sievert's role. The passionate marketing manager took over the top job at T-Mobile US in April 2020, on the day of the finalisation of the merger between the Deutsche Telekom subsidiary and its competitor Sprint, which had been the subject of tough negotiations for years.

He succeeded John Legere as CEO. Legere had earned a reputation as one of the quirkiest, and at the same time most successful, company leaders ever and turned T-Mobile US from a restructuring case into a pearl in the Deutsche Telekom Group portfolio.

A somewhat nervous reaction from investors was therefore expected when Legere stepped down. The company had already taken this into account by presenting Sievert as Legere's successor back in November 2019. T-Mobile US thus signalled continuity above all. Continuity in gaining market share, in revenue and earnings growth, in the now famous „Un-carrier Strategy“ that Sievert had previously been responsible for.

After T-Mobile US had been virtually tailored to become a one-man show under Legere, a new CEO other than a marketing expert would have seemed almost inconceivable, and Sievert's previous role as Chief Marketing Officer made him ideal.

The 55-year-old Sievert started his career at consumer goods giant Procter & Gamble. In addition to positions at IBM and Clearwire, the manager, who was born in Canton, Ohio, worked as Head of Marketing for AT&T Wireless from 2002 to 2005, and is therefore also familiar with the competition. Legere hired him immediately after his start as head of T-Mobile US in 2012.

Under Sievert's leadership, the Deutsche Telekom subsidiary has maintained its growth rate, and surpassed the 100 million customer mark. After the merger with Sprint, T-Mobile US built the first nationwide 5G network. „We're making the rules for the 5G era because we're miles ahead,“ he said back in 2021.

Meanwhile, a new era is now beginning, namely that of fibre optic expansion. While a nationwide 5G network was already a financial feat, not least due to expensive mobile phone licences and the battle with the powerful tower companies, the expansion of fibre optics in such a huge country will swallow up even larger sums. With the fixed network business, Sievert is also entering largely uncharted territory, where a price war such as in mobile telephony is somewhat out of the question, in view of the expansion costs and the necessary refinancing.

Sievert initially capitalised on the company's 5G advantage and sold customers what is known as „fixed wireless access“. However, the momentum here slowed significantly in the latest quarter compared to the previous year, and analysts believe that the technology will only have a market share of 10% at most in the long term. In contrast, they believe that the fibre optic market will be carved up over the next two years. To achieve this, the T-Mobile US CEO will need more than snappy slogans – notably money.

However, he has announced significant share buybacks in the coming years. He plans to spend 50 billion dollars on this by 2027. As he himself said in an interview: „Investors love this story.“ In other words, they are not prepared for compromises. Mike Sievert has to deliver.