The latest 13F season is here, when many money managers issue required reports on their holdings. It can be worthwhile to pay attention, as you might get an investment idea or two by seeing what some major investors have been buying and selling.

For example, consider Lone Pine Capital, founded by Steve Mandel in 1997. Lone Pine is one of the biggest hedge fund companies, and it has reportedly outperformed the S&P 500 handily since inception. Its reportable stock portfolio totaled $23 billion in value as of March 31, 2014. According to its recently released 13F statement, Lone Pine established or added to positions in Jazz Pharmaceuticals plc (NASDAQ:JAZZ), SouFun Holdings Ltd (NYSE:SFUN), and Valeant Pharmaceuticals International (NYSE:BHC).

Jazz Pharmaceuticals has doubled in value over the past year, and with a forward P/E ratio near 14, along with double-digit growth rates, it seems like it has a lot of stock appreciation left in it. The company has a lot to offer, such as successful products on the market (narcolepsy drug Xyrem, for example), a promising pipeline, some promising acquisitions, actual profits, and solid free cash flow. It has a particular focus on orphan drugs, which tend to face little or no competition and can thus command premium prices and generate relatively reliable revenue. Based in Ireland, Jazz Pharmaceuticals even enjoys a lower tax rate. Some speculate that the company might get bought out by a bigger entity, too, as happens relatively frequently in the industry.

SouFun Holdings may not be familiar to you, but it's a China-based e-commerce specialist with a market value near $5 billion, focused on real estate, home furnishings, and home improvement, among other things. The stock has been quite volatile, more than doubling over the past year while trading at a fraction of its 52-week high. Bears don't like that China's real estate market has been accumulating excess inventory, and they weren't thrilled with SouFun's latest earnings report, which featured management tempering expectations. On the other hand, the earnings report also featured revenue growing by 33% year over year and net income surging 46%. The stock's valuation seems compelling, with a forward P/E ratio near six and a 3.3% dividend yield to boot.

Canada-based Valeant Pharmaceuticals International is a giant, with a market cap near $44 billion. It's been in the news more than usual lately after making several bids for Allergan (NYSE: AGN), maker of Botox, breast implants, eye drops, and more. Valeant has several Botox alternatives on the market and is interested in owning Botox itself. Allergan's ophthalmology products can complement Valeant's own eye-care operations, which became substantial with its $8.7 billion purchase of Bausch & Lomb last year. Some think both companies will benefit from the acquisition if it's ultimately approved, but Allergan isn't enthused, and it commissioned reports that suggest Valeant can't grow well on its own without resorting to acquisitions. Bulls see plenty of growth potential, though, and they like Valeant's business model of acquiring products rather than pouring big money into developing treatments on its own that may or may not pan out. Somewhat lost because of the Allergan story is news that Nestle has bought the U.S. and Canadian rights to Valeant skincare products for $1.4 billion.