Every quarter, large money-managers have to disclose what they've bought and sold via "13F" filings. While Fools don't always follow what the big money does, we can often glean an idea or two by tracing their footsteps.

In 2008, Berkshire Hathaway CEO Warren Buffett made a big bet on ConocoPhillips (COP -0.93%). He would call it a "mistake of commission" in his 2008 letter to shareholders, pointing to the terrible timing -- in his words -- of the investment as costing Berkshire investors billions of dollars as energy prices dropped from their highs. At the time, Berkshire held some 84 million shares of ConocoPhillips. A year ago, Berkshire held 24 million shares. 

Tally it all up, and Berkshire sold more than 13 million shares of ConocoPhillips stock in 2013, more than half its remaining stake. Will Buffett sell the remaining 11 million shares in 2014? Should you follow? Let's take a closer look.

Different oil companies do different things
When Buffett invested in ConocoPhillips back in 2008, he wasn't just buying today's ConocoPhillips. In May of 2012, Phillips 66 (PSX -1.86%) went public, and existing ConocoPhillips shareholders were awarded with shares of this new company in a tax-free distribution. Considering that Berkshire still holds some 27 million Phillips 66 shares -- valued at $2 billion -- it's important to talk about what these different businesses do, and why they are attractive (or not.) 

Today's ConocoPhillips is a major E&P, or exploration and production company -- the world's largest, actually -- while Phillips 66 focuses on midstream, meaning moving oil and gas in pipelines from production to refineries, and marketing the finished products to end users. As a comparison, Chevron (CVX -0.41%) is an integrated major, involved in every sector of oil and gas E&P, midstream and refining, marketing, and petrochemical production. 

Why is Buffett moving on?
Taken at face value, it looks like Buffett is shifting away from ConocoPhillips partly due to its focus on an area of the oil business that's extremely sensitive to oil prices. As time passes, more and more of the world's oil reserves are being found in shale rock, or in ultra-deep offshore water, both of which are very expensive to produce from. What this means for ConocoPhillips is that oil prices must stay relatively high in order to both produce at profitable levels and fund further exploration. 

Chevron, on the other hand, has a significant midstream and petrochemicals business, which would offer some downside protection against falling oil prices, much as Phillips 66's midstream and petrochemicals focus does for it. However, Berkshire's Phillips 66 position serves another purpose as well.

Some of those shares are already sold
In December, Berkshire announced it was acquiring part of Phillips 66, in a transaction that would close in the first half of 2014. The company's flow improver business will be rolled under Berkshire subsidiary Lubrizol. This is a very "Buffett" transaction, as the flow improver polymers are important for pipeline operators, as it helps keep oil moving smoothly through the pipelines in different weather and temperature conditions. With oil production steadily increasing in the coming years, this "bolt-on" transaction looks to offer predictable and stable growth in revenues for the future, and at a tax-advantaged benefit as a stock-based transaction.

Final thoughts: Don't project your situation on Buffett's moves
It's important to remember that -- like any other investor -- Warren Buffett's reasons for buying and selling have nothing to do with your situation. Just because he's largely moved on from ConocoPhillips doesn't mean investing in the largest E&P in the world doesn't make sense for your portfolio. Similarly, when those Phillips 66 shares show up as "sold" on Berkshire's 13F in a few months, don't ignore that it was largely the product of a tax-advantaged acquisition that will probably benefit shareholders of Phillips 66 as much as Berkshire investors. 

If you want to invest like Buffett, don't just copy his moves -- copy his method. Find great companies with strong competitive advantages, invest at the best price you can get, and then get out of the way. Buffett made 80% of his massive fortune after he turned 50. His biggest secret? Patience and temperament.