Most people aren't familiar with SAC Capital Advisors, but more are today than were a few years ago. The hedge fund company, run by Steven Cohen, is one of the biggest around, with a reportable stock portfolio totaling $18.5 billion in value as of Sept. 30, 2013.

How did the hedge fund achieve its success? Well, perhaps via some insider trading. Foul play has been alleged, and the company recently pled guilty to charges of wire fraud and securities fraud, agreeing to pay a record $1.8 billion settlement. Meanwhile, several employees are being tried for insider trading.

Still, while you might not want to consider the managers of SAC as your ethics idols, it's not crazy to keep an eye on their investments.

Buys and sells
The interesting moves that SAC Capital made in its last quarter include establishing new positions in online game specialist Zynga (NASDAQ:ZNGA) and railroad supplier Trinity Industries (NYSE:TRN) and selling out of its stake in steel giant ArcelorMittal (NYSE:MT).

Zynga, known for games such as FarmVille, Words With Friends, and Zynga Poker, has had a bumpy history and is sitting in penny-stock territory, with shares below $5 apiece. Still, it's up almost 80% over the past year. Zynga got good news in court a few days ago, as it was found not to have engaged in patent infringement. Its reliance on Facebook has been a concern, and the company is moving aggressively into mobile gaming. It has competition, too, including from Candy Crush Saga creator King. Zynga recently reported that the third quarter might look bad, with revenue down 36% over year-ago levels and monthly active users down 57%. Still, its bottom line was only modestly in the red, its performance topped expectations, and the company is introducing new games, giving investors hope. Bears still worry, though, about a shrinking user base and whether the company will be able to produce more big hits.

Trinity Industries has also seen its stock rise close to 80% over the past year and is benefiting from growing interest in railroad transport, as it sells railcars, among other things. It yields just 1.1%, but that dividend has been raised by double-digit percentages in recent years. American commerce relies heavily on the railroad industry, which offer much more cost-effective transportation than trucking, and the energy industry is increasingly using rails as well. Last year, some 234,000 freight cars transported 167 million barrels of oil, for example! Bulls like Trinity's diversification, as it is also involved in railcar leasing, barge manufacturing, construction services, and more. In its third quarter, Trinity Industries posted record earnings, up 58% over year-ago levels, with revenue up 22% and a railcar order backlog of more than $5 billion.

ArcelorMittal is the world's largest steel producer, and recently yielded 5.4%. The steel industry has struggled in recent years (in part due to slowdowns in China and European financial woes), but recovering global economies are boosting its prospects, as are price hikes. It is becoming more vertically integrated as it boosts its metallurgical coal business, as that's used in the manufacturing of steel. In its third quarter, ArcelorMittal posted a 0.4% decline in revenue and a net loss of $0.2 billion -- 71% narrower than a year earlier. Its core profits were positive, though, topping expectations. Its CFO noted, "The economic indicators do suggest that we are turning a corner and we are cautiously optimistic on the prospects for 2014." A rosy outlook is not held by everyone, though, as analysts at BNP Paribas have downgraded ArcelorMittal from neutral to underperform.