Berkshire was up today over 3%. A shares were up $3940 a share on relatively heavy volume. I didn't see any major news today. I wonder if European buyers stepped in after the conclusion of the European tour. Big rich families who have never really heard of Berkshire.
Another possibility (less likely) is that this trip may have yielded fruit in a pending deal. Rumors could be floating around.
Thirdly is that Kass is covering his short after making some nice money in the short term as it appears more clear that the financials are moving down again.
I just saw it as an interesting anomaly and started wondering why and one of those may be reason.