With most of the fourth quarter of 2012's earnings season behind us, did the Oracle of Omaha put a notch in the "win" column for Berkshire's $77.2 billion portfolio?

Warren Buffett may be the greatest investor alive, but even the Great One (financially speaking) still recognizes earnings season as an important time for investors to take stock of their investments. With earnings already reported for four of Berkshire Hathaway's (NYSE:BRK-B) five largest investments , we can take a look at how Buffett's picks fared during the fourth quarter long before the firm releases its annual statements in late February.

5. Procter & Gamble
The second-quarter results for Procter & Gamble (NYSE:PG) were pretty impressive. The company responsible for Tide, Gillette, and Pampers was able to turn a 2% boost in revenue into a 57% increase in profit, when compared to 2011 results. That kind of improvement highlights the efforts taken by P&G to clean up its operations and improve cost savings, after years of criticism for over-expansion internationally -- something that any investor should be excited to see.

Beyond happy investors, P&G CEO Bob McDonald should be walking tall after the earnings release. Since the embattled CEO faced loud opposition to his position atop the company, including calls for his resignation from activist investor Bill Ackman, after reducing forecasts three times last year -- it is a great sign of leadership that the company has returned to meeting and exceeding expectations. 

4. American Express
The credit card and personal finance company posted pretty lackluster results from its fourth-quarter operations, but there are still plenty of reasons to be excited about where American Express (NYSE:AXP) is headed. The company's revenue only grew 5%, boosted mostly by an 8% increase in card-member spending -- but straggled behind most of its competitors.

AmEx is able to boast one thing among its closest competitors -- a 23% ROI in the fourth quarter. While the company announced planned cuts in its travel department, which would affect its bottom line and boost ROI, the company is clear about its continued focus on investing in the business and moving forward. With an eye to the future and the plans to match, this company should be a favorite among investors.

3. IBM
The tech giant's earnings release performed a feat of Herculean effort. On a day when 21 of the 30 stocks that comprise the Dow Jones Industrial Average were seeing red, IBM's (NYSE:IBM) boost from its better-than-expected earnings pushed the index higher. With a 6.3% increase in profits, the company outpaced expectations and pleasantly surprised investors.

IBM also increased its earnings outlook for the remainder of 2013. While that may be good news by itself, investors should know that the company's new estimates show 2013 earnings up 8% from 2012 -- a nice chunk of change if IBM meets the estimates. And some new information may just shore up IBM's confidence: within the disappointing GDP figures released today, the data still showed consumer spending was up in the fourth quarter -- with private domestic investment in equipment and software up 12% from the third quarter. 

2. Wells Fargo
Oh, the Wells Fargo (NYSE:WFC) wagon is a-comin' down the street all right -- and it did have a little something special to report. The banking giant (and No. 1 mortgage originator in the country) reported net profits increased by 24% in the fourth quarter. And a little something for you -- a 14% dividend bump, which the company announced last week.

But there are some forces working against Wells. While the bank's income boost may have resulted from increased fees from its mortgage and refinancing activities, all of the banks have been struggling with contracting net interest margins -- the difference between the interest percentages a bank takes in though loans and gives out on deposits, etc. It was in this category that investors and analysts found the bank wanting -- with really high expectations blurring some of their judgment on Wells as an investment.

Still waiting on No. 1
Coca-Cola isn't scheduled to release earnings until February, but investors can see already that the fourth quarter was a good one for Buffett. As earnings season rolls on, be sure to make like Warren and keep tabs on how your company picks are making out. As most Fools know, short-term results (like an individual quarter) shouldn't be the end-all be-all of your decision making, but the information you can garner from earnings reports and business plans make them useful research tools.

Fool contributor Jessica Alling has no position in any stocks mentioned. The Motley Fool recommends American Express, Berkshire Hathaway, Procter & Gamble, and Wells Fargo. The Motley Fool owns shares of Berkshire Hathaway, International Business Machines, and Wells Fargo. Try any of our Foolish newsletter services free for 30 days.

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