Bespoke Investment Group has the skinny:

Warren Buffett's Berkshire Hathaway stock holdings were released in the company's quarterly 13F last week. These are the positions as they stood at the end of the first quarter, and below we have calculated their performance so far this quarter. Overall, Buffett's stock holdings have outperformed the S&P 500 this quarter by nearly 1,000 basis points. His positions are up 22.41% versus the S&P 500's gain of 12.96%.

His best performing stock so far this quarter has been Gannett (GCI), which is up 97.73%, but it's also one of his smallest holdings. The next two best performing stocks are big positions. American Express is up 86.57%, and it represents 8% of his overall stock holdings. Wells Fargo is up 83.71%, and it was 16.4% of his portfolio at the end of March. Coca-Cola (KO) is Buffett's biggest holding at 18.79%. Only three of his positions are down so far this quarter -- Costco (COST), Wal-Mart (WMT), and Carmax (KMX)....Go to B.I.G. for the table.