Yesterday, Berkshire Hathaway (NYSE:BRK-B) revealed a new stake in energy giant ExxonMobil (NYSE:XOM). Berkshire's 13F filing stated that the company owned a $3.45 billion interest in Exxon as of the end of September. The purchase accounts for less than 1% of Exxon's shares outstanding.

Berkshire is helmed by Warren Buffett, the renowned value investor. Given the size of this purchase, it's likely Buffett himself directed this investment. Berkshire also reduced its position in oil producer ConocoPhillips during the quarter.

Motley Fool analyst Simon Erickson believes this move speaks volumes for both Berkshire and ExxonMobil. It's another example of Buffett's focus on the long term, and Simon expects Berkshire will likely add to this position over time. Given Exxon's steady returns and long-established dividend, Simon thinks it's a great candidate for any portfolio.