Subject: IV by the repurchase method
Warren's conservative estimate of IV can be inferred from his stock repurchases. Berkshire makes fewer repurchases when the P/B is higher, and it has paused repurchases altogether when the P/B is too high, as in April and May of 2022. The highest price/beginning book for the quarter that Warren has paid is 1.49 (which he paid in November 2022), and the highest price/ending book for the quarter that Warren has paid is 1.51 (which he paid in September, 2023). Warren has said that he would not repurchase stock at a "mere" 5% discount to IV, so his repurchase at 1.51 times BV implies an IV of at least 1.59