As long as Class B shares are below 89.37, Buffett would be buying the shares. This is the floor.
Simple math - (1.2 * book value)/1500.
And as long as the stock stays below this price, expect the book value to go up in the next quarter due to buy back. Also, take in to consideration that the entire market is ahead compared to last quarter. Won't be surprised to see a 5% or higher jump in book value in Dec 2012 quarter.
Cool and lowest risk way to invest in the market and still participate in Insurance, Rails road, chemicals, housing etc market.
I expect the stock to stay under 89.37 at least for this week and the next as people sell for cap gains. So, the book value may jump higher than 5%. Wow! I love this ride with Zero loss over the long haul!.