MILLBURN, N.J. ( Stockpickr) -- The snow is melting, the days are longer, oil prices are rising, Apple unveiled the second generation iPad, and exogenous events at opposite ends of the world -- Japan and Libya -- are rocking the world, literally and figuratively. For me, this signals an opportunity for some portfolio spring cleaning.Don't get me wrong. I do not believe that the market is "rolling over" or is overvalued or that the bull market has come to an end. My research indicates that the equity markets are in the beginning of a multiyear bull market. Those exogenous events will be resolved, and the world will not come to an end. But as famed economist John Maynard Keyes is attributed to have said, "When the facts change, I change my mind. What do you do, sir?" Related: Two Pair Trades to Play It Safe In managing a portfolio of 30 to 40 stocks, fundamentals will always change. Events, either micro to a company or macro to an economy or sector, will impact some of those stocks. Hence, I have sold some stocks. Conversely, opportunities have appeared for other stocks and sectors. As a result, I have made several portfolio changes over the past two weeks. Here is a listing of the transactions that I have initiated and the reasoning behind my actions. Ulta Salon Last year I included Ulta Salon ( ULTA) in my list of fad stocks. At the time, I wrote: "Right now Ulta Salon and Sally Beauty Holdings ( SBH) are in a favorable industry in an economy that is turning around. That too shall end, but until then, these stocks could be a 'pretty' investment." Ulta Salon has consistently delivered excellent earnings and recently raised its guidance. The company is growing earnings at a rate of 25% to 30%. However, with the stock selling at 30 times current year's earnings estimates and having a 65% gain in my holdings, I thought that it would be prudent to take profits. Ulta, which showed up on a recent list of five stocks hitting highs even amid turmoil, is one of TheStreet Ratings' top-rated specialty retail stocks.