From Baron Funds' first quarter letter: In the quarter, we sold our position in American Tower Corp. (NYSE:AMT). We owned the stock for the last 10 years and made about eight times our money in that period, one of our most successful investments in the life of the Fund. We actually got involved 15 years ago when the company was spun out of a company called American Radio. Little did we know what it would become. American Tower recently converted to a REIT, and we now believe it is fairly valued, so it was time for us to move on.