Billionaire tech mogul Michael Dell appears to have generated a huge return on a few television stations he bought over the past six years.
Dell’s personal investment fund, MSD Capital, has acquired more than 20 station since 2011, spending at least $90 million, according to the Wall Street Journal.
The stations didn’t amount to much in the era of broadcast television, but each possessed an increasingly valuable commodity in the current mobile Internet boon: a license to use specific airwaves in the 600 MHz band. On Thursday, sales of those rights by 10 of Dell’s TV stations to wireless carriers brought in $441 million at a just-completed federal spectrum auction.
Overall, TV broadcasters sold rights from 175 stations for a total of almost $20 billion, with the station owners keeping half of the money. Besides Dell, other major sellers included Sinclair Broadcast Group (SBGI), Comcast (CMCSA), and 21st Century Fox (FOX). The stations now have a 39 month transition period to switch to another frequency or go off the air.
Dell, who made his fortune through the personal computer company that he started in his dorm room, created MSD Capital in 1998 to invest in all manner of opportunities, ranging from public stocks and real estate to more esoteric plays like the TV station license gambit.
Get Data Sheet, Fortune’s technology newsletter.
The FCC’s incentive auction for the TV spectrum rights attracted mostly major broadcasters as sellers and wireless carriers like T-Mobile (TMUS) as buyers, but a few investment funds also got in the action. While Dell’s fund was a seller, Columbia Capital, a wireless industry private equity fund, got in on the action as a buyer, spending $1 billion to acquire eight licenses.
Fortune reached out to MSD Capital for comment and will update this story if any is received.
Ultimately, the auction didn’t go as well for broadcasters as some analysts had expected. Early forecasts for the bidding estimated that carriers would spend $30 billion to $40 billion for the airwaves. But with Sprint (S) and Verizon (VZ) making no bids and AT&T (T) keeping its activity modest, the auction raised only $20 billion.