July 28 (Reuters) - Berkshire Hathaway will sell about one-third of its more than $4 billion stake in VeriSign, an internet infrastructure and domain name registry company that Warren Buffett's conglomerate has invested in since 2012, VeriSign said on Monday.

VeriSign, based in Reston, Virginia, said the sale of 4.3 million shares was intended to reduce Berkshire's stake to below 10%, a threshold that triggers regulatory obligations.

Berkshire may sell an additional 515,032 shares to meet demand. VeriSign will receive no proceeds from the sale.

As of March 31, Berkshire owned 13.29 million VeriSign shares, or about 14.2% of the company, regulatory filings show.

Those shares were worth about $4.07 billion based on VeriSign's closing price of $305.98 on Monday.

In after-hours trading, VeriSign fell 6.7% to $285.42.

Berkshire ended March with $347.7 billion of cash, and through that month was a net seller of stocks for 10 straight quarters.

The VeriSign investment may have been spearheaded by one of Buffett's portfolio managers, Todd Combs or Ted Weschler. Berkshire had been adding to the stake as recently as January.

Buffett, 94, has run Omaha, Nebraska-based Berkshire since 1965. He is expected to step down as chief executive at year end, and be replaced by Vice Chairman Greg Abel, 63. Buffett would remain chairman.

JPMorgan Securities is underwriting the VeriSign share sale.