Earlier quoted context omitted.
Wow I didn't realize this, but it appears to be true: https://en.wikipedia.org/wiki/MSNBC "Microsoft divested itself of its stakes in the MSNBC channel in 2005 and in msnbc.com in July 2012." I thought their Edge browser was still promoting links to MSNBC, but looking at Edge now, I see the links are to MSN.com which is a completely different thing and actually a Microsoft news portal. Interesting the news channel is…
When you've spent millions and years promoting a brand ID, you don't change it just because ownership changed. (Another example: If I understand correctly, General Electric doesn't have anything to do with GE-branded light bulbs. They sold the business. But the buyer wanted more than the factory and the distribution arrangements, they wanted the name that people recognized.)
NBC's chime was developed when it was owned by GE in the 1930s (the notes are G-E-C – General Electric Company). When GE sold its interest, that chime continued to be used.
GE later regained control of NBC, and once again sold the last of its interest to Comcast a few years ago. But the G-E-C jingle remains unchanged, the first audio trademark granted in the US.