The latest numbers are in for Berkshire Hathaway (NYSE:BRK-A)(NYSE:BRK-B), revealing what stocks Warren Buffett bought and sold during the last few months of 2014. But the biggest news and move may not be news or a move at all.

The unknown unload
Last Tuesday, Buffett's company filed its 13-F form, which shows what stocks it held as of Dec. 31. As previously discussed, the biggest news on the buying front was the additional purchase of roughly $1 billion more of both IBM and Deere & Company.

Source: Flickr / Minale Tattersfield Roadside Retail.

Yet the most noteworthy news was the nonexistence of ExxonMobil (NYSE:XOM) from the Berkshire filing. A cursory glance reveals that it went from being the seventh largest position in the $110 billion stock portfolio, with a market value of nearly $4 billion at the end of September, to entirely absent in just three months' time.

As a result, we were met with headlines such as "Warren Buffett Sells Entire Exxon Stake" from Bloomberg, and "With Oil Prices Plunging, Warren Buffett's Berkshire Dumped Exxon Stake" from Forbes.

But what if I told you none of that may be true?

The key distinction
You see, all we truly know is that a position in Exxon wasn't disclosed in the 13F filing. But that doesn't mean Berkshire didn't have a position in it.

As wonderfully discussed in the paper Do Institutional Investors Have an Ace up Their Sleeves? by Dr. Wei Jiang of the Columbia Business School and others, just because a position is absent from a 13F filing doesn't mean it's actually absent from a company's portfolio. The authors note (emphasis added):

The quarterly reports, filed to the Securities and Exchange Commission (SEC) on the Form 13F, disseminate the public information about holdings and investment activities of institutional investors. An exception to the rule, however, provides confidential treatment of certain holdings through amendments to the original Form 13F. When adequate written factual support is provided for certain holdings, this provision allows the institutions to delay the disclosure of those holdings, usually up to one year.

In other words, so long as Buffett, Charlie Munger, CFO Marc Hamburg, investment lieutenants Todd Combs and Ted Weschler, or anyone else at Berkshire notify the SEC that Berkshire didn't feel comfortable disclosing where its Exxon position stood because of how the market might react, then there is freedom to wait up to a year to say exactly what that position was.

This is critical, because Berkshire did this very thing with Deere & Company in the third quarter. In the 13F filing from Nov. 11, for the period ending Sept. 30, no position in Deere was disclosed. As a result, many -- myself included -- said the $360 million Berkshire Hathaway position in Deere had been sold off in its entirety.

But because of an amended third-quarter 13F filing released last week, we now know that Berkshire didn't decrease its stake in Deere by 100%, but it actually grew its stake by 90% -- a complete reversal from what was first reported:

Buffett and his fellow managers know how closely Berkshire's stock moves are monitored, so it's entirely sensible that if they wanted to grow their stake in Deere, they wouldn't want anyone to know about it because others may follow suit and inflate the price of the stock.

The Exxon exception
To bring it full circle, investors also must know that when Buffett first began buying Exxon in the second quarter of 2013, it wasn't disclosed until November 2013, through -- you guessed it -- an amended 13F filing.

Two of Buffett's best-known quotes are "Only buy something that you'd be perfectly happy to hold if the market shut down for 10 years," and "We simply attempt to be fearful when others are greedy and to be greedy only when others are fearful."

With those in mind, knowing Buffett owned Exxon for all of 15 months and energy stocks are taking a beating because of falling oil prices -- Exxon is down 10% over the past six months -- is it more likely he sold his stake entirely, or is it actually more likely he's just buying more and just doesn't want you to know?

That's up for you to decide, because ultimately, we shouldn't make our investment decisions by blindly following one example, even if that example is Warren Buffett.

Personally, I'd go with the later, and in three months' time, we'll probably know for sure.


Patrick Morris owns shares of Berkshire Hathaway and ExxonMobil. The Motley Fool recommends Berkshire Hathaway. The Motley Fool owns shares of Berkshire Hathaway and International Business Machines. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.