Buffett says this kind of stuff publicly. But his own fund moves in and out of investments all the time.
>But it's true. I could name half a dozen people that I think can compound $1 million at 50% per year -- at least they'd have that return expectation -- if they needed it. They'd have to give that $1 million their full attention. But they couldn't compound $100 million or $1 billion at anything remotely like that rate.
A lot depends on the details of who's doing what.
Wholly owned companies list: https://berkshirehathaway.com/subs/sublinks.html
0: In terms of BRK's overall wealth, it's still in the many billions of dollars.