Investors often use Berkshire Hathaway's quarterly-filed Form 13Fs to track Warren Buffett's trading activity. Buffett has been a net seller of stocks for nine consecutive quarters, which has ballooned Berkshire's cash pile to $334 billion.

Tens of thousands of people will descend on Omaha, Nebraska, to attend the annual shareholder weekend for billionaire Warren Buffett's Berkshire Hathaway. Buffett, 94, is expected to answer shareholder questions over four and a half hours at Berkshire's annual meeting on Saturday.

Warren Buffett has been accumulating cash over the last couple of years. Stephen Wright thinks a big announcement could be on the way.