For the most part, Warren Buffett's portfolio has had a pretty good year, along with the broader market. Now, he's looking for one of his picks to make big gains -- but not with his bread and butter, U.S. companies. This U.S. company, Moody's Corp., has tacked on gains of nearly 30% this year -- but it hasn't been with its traditionalsuccess metrics. Moody's has struck deals overseas, to access credit data markets in places like India and China. Now, it aims to build scale, and the emerging markets M&A strategy is boosting Moody's top line overseas. For Berkshire Hathaway, Moody's rates very highly this year.