Buying Back Shares at a Higher Breakpoint Than Berkshire's Book Value Per Share?

Berkshire is authorized to share a purchase program. Originally aimed at buying back shares at prices no higher than 10% premium to the firm's most recent book value per share. Figure that was subsequently increased to repurchase shares at price no higher than 20%. There's been relatively little share repossession activity during the last four and a half years. Even as the shares dipped down below the 1.2 times book value threshold during both January and February of this year, if you base it on a buyback price calculated on Berkshire's book value pershare at the end of 2015.