Geico, and pension plans of other Berkshire Hathaway units bought nearly $30 million of shares of domain-name registry firm VeriSign.

VeriSign is ranked 5th in the S&P 500 for the highest profit margin, at about 56%, tied with Nvidia, according to third-quarter financial data.

Warren Buffett’s Berkshire Hathaway Inc. has been busy over the past week buying stock in an internet domain-name registry company, to extend its lead as the company’s largest shareholder.