BRK.B is supposed to be 1/30th of BRK.A. The A shares are convertable to the B shares at a 30x conversion, which ensures that the B shares never trade at a premium. Instead, the B shares typically trade at a 1-3% discount the A shares. In the last week, however, the B shares have plummeted and now trade at almost an 10% discount, versus only 1% discount on a few days ago on Tuesday's close. WTF? Anyone have any idea on the reason for this? This is a massive change in just a few days, and seems like it must be more than just liquidity related. Any know?