One of Berkshire's two new positions last quarter was Starz. Buffett picked up 5.62 million shares of the media and entertainment company, a $129 million stake that amounts to more than 4.6 percent of Starz's outstanding shares. The new position came onto Berkshire's portfolio thanks to the firm's spin-off from Liberty Mediaback in January; it's the fund managers' decision to keep Starz that's telling.

Starz was originally launched as a premium cable channel, broadcasting feature films and a smaller set of original TV series. Today, the firm's umbrella also includes the Encore and MoviePlex brands, with 17 cable channels of various flavors in all. The biggest feather in Starz's cap is its ability to secure home distribution agreements with content producers. Those agreements ensure that substantial content flows to the 57 million combined subscribers who pay monthly fees to receive the channel.

Original content creation offers some big opportunities for Starz—if the company can pull it off correctly. Series such as Spartacus and Da Vinci's Demons have been well-received by viewers, but they still lag significantly behind the original content put out by rivals like HBO and Showtime. With the largest pay-TV subscriber base in the country, Starz has the audience in place already; it just needs to push its content harder to increase the stickiness of that subscriber base.

Growth has been somewhat slow at Starz in recent years, and Berkshire's focus on cash-generating investments makes Starz an interesting hold for the firm. It'll be worth keeping an eye on how this position gets managed.

Chicago Bridge & Iron

The only truly new position in Berkshire Hathaway's portfolio last quarter wasChicago Bridge & Iron, a $6.8 billion construction and engineering firm that, despite its Windy City name, is actually domiciled in the Netherlands. Buffett and company took on a 6.51 million share position in CBI last quarter, which works out to a $404 million grubstake at current price levels. That ownership represents 6.03 percent of CBI's total market value—a substantial position indeed.

CBI is a worldwide engineering and construction firm. The firm's specialty comes in constructing energy facilities around the globe—but it's got a particular niche in building facilities that handle liquefied natural gas. Around 20 percent of CB&I's sales come from building steel plate structures that industrial customers use to store material. That hefty energy sector and industrial exposure has some consequences, both good and bad; most importantly, it means that the firm benefits when commodity prices are high and energy firms are investing heavily in infrastructure projects.

In recent years, CB&I has begun reaching away from its core construction and engineering business, adding on new ways to service its existing petrochemical customers. The Lummus Technology unit, for instance, sells gas processing and refining technology. While it's still a small chunk of CBI's revenues, it's a lucrative one. The recently closed $3 billion acquisition of Shaw Group adds considerable nuclear building expertise to CBI's offerings. That's attractive positioning to own as power companies invest in low-cost power generation.

DirecTV

While DirecTV isn't a newly initiated position for Berkshire Hathaway, it was a major conviction buy last quarter. The firm added 3.24 million shares of DTV to its portfolio, raising its holdings in the firm by almost 10 percent to $2.1 billion. That increase gives Buffett's firm 6.5 percent ownership in the satellite TV carrier.

DirecTV operates the biggest satellite television network in the U.S., with close to 20 million subscribers. DirecTV also owns stakes in Latin American satellite TV providers that serve more than 11 million subscribers. There's a Starz connection here, too. Both firms once fell under the Liberty Media umbrella until they were respectively spun off (LMCA, incidentally, remains a Berkshire position).

DirecTV has managed to churn out some impressive performance over the last few years. The company targets bigger spenders who spend more per household for TV services than the average. As a result, DTV gets access to ample cross-selling opportunities that dramatically widen margins. Because the firm is a satellite firm, it's also able to grow its subscriber base without having to pay the massive capital expenditures that similar fixed-line services have to shell out.

While new customer acquisitions are pricey (the firm subsidizes equipment), the road to profitability is far shorter than at rival services like Verizon's FiOS. With impressive relative strength in play at DTV, this stock's outperformance looks likely to reverse in the near-term.

DaVita HealthCare Partners

DaVita HealthCare Partners remains one of Ted Weschler's favorite stocks in 2013. The portfolio manager added 1.37 million shares of the dialysis center operator to Berkshire Hathaway's portfolio in the first quarter, adding onto his existing stake by 10%. That brings Berkshire's total position in DVA to 14% of outstanding shares.

There's a limit on how much Weschler can buy. Earlier this month, he agreed to limit Berkshire's stake in DaVita to 25%, and limit his shareholder activism in the firm. That news quelled rumors that DVA could be a buyout target for Berkshire, but this quarter's position increase shows that Berkshire's investment team is still bullish on this business.

(Read More: Health-Care Industry Game-Changers)

DaVita runs more than 1,800 clinics and in-patient hospital dialysis units across the U.S. The firm's clinics are unique in that they serve patients who suffer from chronic long-term kidney issues. Typically, the only way around dialysis is a kidney transplant, and demand vastly outstrips supply of transplant organs in this country. That means that DVA's nearly 140,000 patients are likely to stick with its facilities for the long term. Health care tends to be a sticky business—barring a major bad experience, patients are likely to stay with their providers—which makes DVA's revenues consistent and predictable in large part.

The 2012 merger with HealthCare Partners changes DaVita's concentration slightly. The new physician management arm now makes up around a quarter of DaVita's revenues. That increased scale justifies the increased share price that investors are paying for DaVita. I'd expect Berkshire's buying of DaVita to keep on going in 2013.

VeriSign

It's been a strong year for shareholders in VeriSign— Berkshire Hathaway included. Berkshire added 3.69 million shares of VeriSign to its portfolio as a new position last quarter, and it more than doubled its stake in the most recent quarter, piling on another 4.49 million shares. That gives Buffett and company a 5.35 percent ownership stake in VeriSign's outstanding shares.

In a nutshell, VeriSign's business is the Internet.

VeriSign is one of the biggest Internet infrastructure firms in the world, maintaining a central directory of all domains and many of the systems that run them. The company is essentially the gatekeeper to owning a .com Web address, and as a result, VeriSign is able to collect a fee for each of the more than 110 million domains that fall under its purview.

While the introduction of a new category of "top level domains" (such as .aero for aviation businesses or .mobi for mobile websites) does increase the competition faced by VeriSign, the new naming options aren't likely to steal share from the dot-com domains. Instead, firms are likely to just register both names. VeriSign's exclusive contracts with ICANN offer an attractive economic moat for the firm. Because increases in registration fees are built into those contracts, VeriSign will be able to generate attractive growth over the course of the next several years without needing to work for it.