OMAHA, Nebada (AP) -- Warren Buffett is sending a clear signal that he believes Berkshire Hathaway’s stock is undervalued by announcing a plan to repurchase stock for the first time since taking over the firm in 1965.

Berkshire said Monday that the company Buffett leads will repurchase its Class A and B shares anytime they are trading at less than 110 percent of book value.

Berkshire’s Class A stock surged 8.1 percent, or $8,129, to close at $108,449 Monday. Its more affordable Class B shares rose $5.72, or 8.6 percent, to $72.09.

Book value is a measure of a company’s value that Buffett often cites because it is similar to the intrinsic value figure he calculates to determine if an investment is overpriced. At the end of June, Berkshire estimated its assets were worth $98,716 per Class A share after liabilities were deducted.

That estimate doesn’t include Berkshire’s $9 billion acquisition of specialty chemical maker Lubrizol that was completed earlier this month.