Google's

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Sergey Brin disclosed in a government filing the sale of roughly 150,000 Class A shares of the company he co-founded.

In two Form 4s filed late Tuesday, Brin reported 30 separate transactions in which he sold 149,700 shares at prices congregating around $178. At that price, the transactions would have gross proceeds of about $26.6 million.

The sales occurred on Monday.

Brin and co-founder Larry Page said in a Nov. 19 filing that they planned to unload 7.2 million Google shares over the next 18 months, transactions that would reap well over $1 billion apiece if consummated in the $170 range. Brin's latest round of sales was carried out in blocks ranging from 100 to 16,234 shares over the course of one trading day in which the price of the stock ranged from $176.02 to $180.70.

All of Brin's sales comprised Class A shares, by far the smaller category of equity he controls. According to the filing, Brin owned 250,000 Class A shares after the last sale was completed. By contrast, Brin, Page and CEO Eric Schmidt owned 90.5 million of Google's super-voting Class B shares at the time of the Nov. 19 filing.

Brin and Page each sold more than 480,000 shares in Google's IPO -- sales worth $41 million to each of them.

Google closed at $171.43 Tuesday. The stock went public in August at $85 a share.