Naming the favourite share of the world’s richest man

Ever wondered which is the richest man on earth's favourite share?

Bill Gates, founder of Microsoft, tops the Forbes billionaire's list with net worth of $79.4bn. Although he retired as CEO seven years ago, Gates is still on Microsoft's board where he is described as its "technology advisor". He owns 300 million Microsoft shares worth $16.5bn, but has been progressively reducing his holding over the years.

Outside of Microsoft, Gates has a share portfolio worth $17.2bn spread between 16 other US-listed companies. A hefty 60% of the portfolio is invested in just one share: Berkshire Hathaway. Put differently, Gates has entrusted an eighth of his total wealth into 79.3m of Berkshire's B shares, currently worth $10.4bn.

The ultimate insider, Gates serves as a director on the Berkshire board chaired by his good pal Warren Buffett. In the three months to end September, Gates bought another $1.5bn worth of Berkshire shares. The stock has fallen 10% this year. What more encouragement do you need?