Berkshire's performance has been pretty much identical to the average S&P 500 stock in the last 7, 8, 9 months.
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We are talking about the last month/4 weeks. During that time there was nothing identical at all. Instead a sharply(!) rising Berkshire, in sharp contrast to the months before --- and the "coincidence" that this rally started exactly(!) when the Nasdaq started to fall.

Not so much, that's my point. Berkshire has been market tracking, if you consider "the market" to be other stocks rather than a few specific giants. Berkshire's stock price was a little weak in the summer for a while, then that entirely unwound, netting to nothing. The unwinding looks like a big rally, but a few percent here or there is just noise, some stocks move that much in a day.

The unwinding only looks like a big stretch of outperformance because the cap weight index has behaved oddly for a month because a few specific big companies had weak share prices. Phrased another way, the *average* S&P 500 firm has outperformed the cap-weight S&P by over 8% in the last month. Berkshire isn't having a unique moment of glory. There is no obvious reason to think it has anything to do with perceptions of the new boss or indeed anything truly company specific. "Not a hypercaler" with a tiny pinch of "risk off" more than explains it.

Jim