T-Mobile CEO John Legere is stepping down, and that's not necessarily a welcomed site for investors, who will certainly want to see a success out of the recently completed Sprint acquisition.
The stock was falling as much as 1% Monday, before the losses moderated to 0.54% to $77.65.
There's a reason for that.
Here's what Legere is leaving behind.
T-Mobile has grown to a $66 billion company by market cap, as it has gained 264% since Legere took the helm in September 2012.
That puts to shame the gain on the S&P 500 since that time of 114%.
Legere oversaw six acquisitions since he took over.
Those include the Sprint purchase for about $26 billion, as well as smaller ones like Metro (now "Metro by T-Mobile"), Suncom Wireless Holdings, Layer3 TV and PushSpring.
The T-Mobile and Sprint tie-up has been an uphill climb, as the Department of Justice took a hard look at the deal from an anti-trust perspective.
Still, Legere and company operated the business in that time effectively.
Revenue growth didn't skip a beat, moving from $40.3 billion in 2017, gradually up to $44.9 billion expected for the full year of 2019.
This growth rate is relatively in line with standard expectations for a large and stable telecom company like T-Mobile.
Current Chief Operating Officer Mike Sievert will take over on May 1 May 2020.
He'll oversee the integration of Sprint while running the core business.
Investors are certainly hoping to see potential synergies from the deal pan out.