Subject: Re: Brk up again, does anyone have a clue
Two factors

Main one: market go up. If you're looking for a rational explanation of that, don't ask me.

Secondary: Berkshire's period of underperformance that started in mid April ended around two weeks ago and reverse. So at the moment, Berkshire goes up just a bit more than whatever the market does.

Berkshire is trading at almost spot on $500 per B share.
That's about 20% (1.72 standard deviations) above its average valuation level in the last 20 years, using the "smoothed real value per share" sort of view. I can post a graph if anyone is interested.
The current rally might go on for quite a while (or not, beats me). But I wouldn't count on the high prices lasting all that long.

Jim