You've probably seen the headlines. Famed billionaire investor Warren Buffett has been loading up on Apple (NASDAQ:AAPL) stock. But just how many shares has he bought through Berkshire Hathaway (NYSE:BRK.B) (NYSE:BRK.A)?

Millions of shares and billions of dollars

A glance at Berkshire's most recent SEC filing with updates on the company's common stock investments reveals Apple has become one of Berkshire's largest positions, valued at over $7 billion. But Buffett didn't stop at the 61.2 million Apple shares reported in the annual 10-K filing. The Berkshire chairman and CEO has since more than doubled his position in Apple, growing Berkshire's slice of the tech giant to a whopping 133 million shares, Buffett said in a CNBC interview this week. This puts Berkshire's stake in the $729 billion company at about 2.5%.

Apple store in Santa Monica

Image source: Apple.

There's no doubt this investment in Apple is an important wager for Berkshire. With Apple stock trading at about $139 at the time of this writing, that's an $18.5 billion position, second only to Berkshire's $29 billion position in Wells Fargo and edging out Berkshire's $17 billion position in Coca-Cola. Berkshire's fourth, fifth, and sixth biggest holdings are IBM, American Express, and Phillips 66, valued at about $13 billion, $11 billion, and $6 billion, respectively.

Still a fraction of Berkshire's whole business

Despite being Berkshire's second-largest holding now, investors shouldn't expect Berkshire's performance to be heavily influenced by Apple stock. Berkshire is a large company in its own right, with a market capitalization of $432 billion. Further, Berkshire's results remain more closely tied to its wholly owned subsidiaries than its equities portfolio.

First in importance at Berkshire is its wholly owned insurance businesses, which include giants Berkshire Hathaway Reinsurance Group, General Re, GEICO, and more. Together, Berkshire's insurance businesses ended 2016 with $91.5 billion of float, or premiums collected upfront that can be invested, and generated a combined underwriting profit of $2.1 billion.

Then there's Berkshire's regulated, capital-intensive business, which includes BNSF railroad and Berkshire Hathaway Energy (Berkshire's 90%-owned utility business). These two companies alone accounted for 33% of Berkshire's after-tax operating profits in 2016.

BNSF locomotive on a railway.

Berkshire agreed to acquire BNSF in 2009 in a deal that valued the railway company at $34 billion. Image source: BNSF.

And Berkshire's subsidiaries don't stop here. Berkshire's manufacturing, service, and retailing operations "sell products ranging from lollipops to jet airplanes," Buffett said in his 2016 annual letter to shareholders. This "motley crew," as Buffett calls it, generated $5.6 billion in operating profits for Berkshire. Or, as explained in Berkshire's 10-K filing, their combined results can be summed up like this:

Viewed as a single entity, the companies in the manufacturing, service and retailing group are an excellent business. They employed an average of $24 billion of net tangible assets during 2016 and, despite their holding large quantities of excess cash and carrying very little debt, earned 24% after-tax on that capital.

Finally, Berkshire's finance and financial products businesses generated a nice $2.1 billion of net income for Berkshire in 2016.

So, yes, Buffett's bet on Apple is massive next to Berkshire's other common stock investments. And the massive position is certainly a signal of Buffett's great confidence in the tech giant's long-term potential. But both Apple and Berkshire investors should keep in mind that Berkshire is still far more than an $18.5 billion bet on Apple.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.