UPDATE 1-Warren Buffett donates $1.5 bln Berkshire shares

* Buffett donates 516,572 Class B shares

* Buffett still owns $36 billion Berkshire stock

NEW YORK, July 2 (Reuters) - Billionaire investor Warren Buffett has donated about $1.5 billion of Berkshire Hathaway Inc (BRKa.N) (BRKb.N) stock, in connection with his 2006 pledge of his holdings to charitable causes.

According to a regulatory filing, Buffett on Wednesday donated 428,688 Berkshire Class B shares to the Bill and Melinda Gates Foundation, and 87,884 shares to four family charities.

Following the donations, Buffett still held 350,000 Class A and 1,501,532 Class B shares of Berkshire, together worth about $36.1 billion based on Wednesday closing prices.

Buffett said he still has a 25.8 percent stake in Berkshire, and 31.6 percent of the company's voting power. A Class B share is worth about 1/30th of a Class A share.

Buffett, 78, has built Omaha, Nebraska-based Berkshire into a conglomerate with close to 80 businesses that sell such things as insurance, clothing, ice cream and paint, and which owns tens of billions of dollars of common stock.

Forbes magazine in March called Buffett the world's second-richest person, trailing only Bill Gates, who is also a Berkshire director. Gates co-founded Microsoft Corp (MSFT.O).

(Reporting by Jonathan Stempel; Editing by Richard Chang)