A filing with the SECtonight reports that as of December 31, 2010, BlackRock "beneficially owned" 68,430,861 Berkshire Class B shares. The 13G formused for the disclosure indicates BlackRock is a passive investor.
At today's closing price of $82.45, the shares would have a market value of $5.6 billion.
That appears to be an increase. CNBC.com's list of top institutional holders of Berkshire Bs, which doesn't take this latest filing into account, has BlackRock owning 53.4 million shares, about 5.1 percent of shares outstanding.
Warren Buffett is listed as owning 50.4 million shares, or 4.9% of those outstanding. But that's just his Class B holdings. He also has almost 37 percent of the higher-prices Class A shares, a position worth almost $42 billion.