VeriSign shares fell on Tuesday after Warren Buffett's Berkshire Hathaway sold nearly one-third of its stake in the internet infrastructure and domain name registry company for $1.23 billion.

VeriSign Inc. shares drop as Berkshire Hathaway sells chunk of holdings. Sale aims to reduce ownership below 10% regulatory threshold.

Here are some of the stories Wall Street is watching on Tuesday, July 29. Warren Buffett's Berkshire Hathaway (BRK-B, BRK-A) is trimming more of its stake in VeriSign (VRSN). Shares of Novo Nordisk (NVO) are being pummeled after warning of a slowdown in sales of its weight-loss drug in the US.