Berkshire is forming a rounding top right now. The rounding top looks just like it sounds -- the pattern indicates a transition in control from buyers to sellers, and it triggers a sell on a move through its base. That's the $110 level in Berkshire's case. The 50-day moving average is still acting like a solid proxy for support in Berkshire Hathaway. I'd suggest selling (or shorting) on a move through that level.If you decide to make an active bet against shares, keep a protective stop on the other side of the 50-day. Berkshire is likely to correlate pretty heavily with the S&P in July, which means that the big index could drag it below support next week.