If there is one man alive who is considered to be the greatest long-term investor out there, Warren Buffett comes to the minds of many investors.

So, what happens when investors see big trends taking place inside of the full stock holdings of Berkshire Hathaway Inc. (NYSE: BRK-A)? And what happens when they think of it in the sense of oil and gas?

It turns out that Buffett has somehow and some way become selectively more aggressive about oil, gas and energy over the recent months. In fact, if you just dialed out the noise and studied buying trends you might think that he may have tried to call a bottom in the energy patch.

Two main issues here come to mind, one of which is Phillips 66 (NYSE: PSX). Kinder Morgan Inc. (NYSE: KMI) is the second thing to consider. But of course there are other issues as well. Suncor Energy Inc. (NYSE: SU) in Canada is another, and there is of course the old dilemma of Exxon Mobil Corp. (NYSE: XOM) that goes back to 2014.

In terms of energy infrastructure bets by Berkshire Hathaway, there was the $26 billion acquisition of Burlington Northern Santa Fe (BNSF). Buffett called this an all-in bet on America, but what it got a huge bump from all the oil being shipped by rail out of the Bakken Formation. This business is now slow again as Bakken activity has been lowered massively. Still, Buffett and BNSF will be there when that picks up again.

Phillips 66 has already turned into a larger stake than what was represented at the end of 2015. At the time the Buffett stocks were released, the stake had grown to some $5.5 billion in value, taking it north of 10% of the shares outstanding. By investing in the refining and infrastructure aspect, Buffett’s signal here is that he is wanting to profit off of the energy sector whether oil prices trend up or back down.

Buffett’s stake in Phillips 66 had at one point been classified as an elimination in 2015. Then it was later revealed that Buffett got the stake classified with the SEC as confidential, so that he could increase his stake to something of size. Phillips 66 has a market cap of about $46 billion.

24/7 Wall St. pondered about what it was that Buffett, or his team, might have been thinking in taking a decent stake in Kinder Morgan. The first thought is that this is a corporation now, since it removed its master limited partnership status. It is also one of the best run companies in its sector, and Richard Kinder is considered by investors and industry insiders alike to be one of the top energy CEOs around.