In what has proven to be a timely and opportunistic move, famed investor Warren Buffett has been loading up on Apple (AAPL -1.00%) stock through his holding company, Berkshire Hathaway (BRK.B 0.50%) (BRK.A 0.55%). Putting the spotlight on Buffett's stock-picking prowess, the stock has seen an astronomical rise, climbing about 85% since Berkshire started buying Apple in early 2016.

You can bet Berkshire has made some serious money on the investment.

But how many shares of Apple does Berkshire own today? And what is Berkshire's position in Apple stock worth? Here's a look at what we know about Berkshire's position in the tech giant as 2017 comes to a close.

Apple's Phil Schiller shows off iPhone X at a product launch event

An Apple executive shows off the iPhone X. Image source: Apple.

Berkshire's love affair with Apple stock

Berkshire's first purchase of Apple stock was relatively small -- at least when compared with Berkshire's top equity holdings at the time. Berkshire purchased 9.8 million shares of Apple stock, worth about $1 billion, in the first quarter of 2016. The position was initiated by one of his two investing lieutenants, Todd Combs or Ted Weschler, each of whom was managing about $9 billion at the time.

Buffett later said that it was this purchase by one of his lieutenants that got him interested in the stock. With far more money at his disposal than his lieutenants, Buffett quickly built up a much larger position in the tech company after looking into the stock. By the end of 2016, Berkshire owned 61.2 million shares of Apple, purchasing the stock between prices of $90 and $118. And then Berkshire really went all in, doubling its position in Apple during the first quarter of 2017.

Buffett has continued to be a buyer of Apple stock, purchasing 3.9 million additional shares as recently as Berkshire's third quarter of 2017.

In total, Berkshire's position in Apple stock has swelled to more 134 million shares, worth about $23.5 billion. Apple is now Berkshire's third largest equity holding, second to a $25.5 billion position in Kraft Heinz and trailing further behind a $28.6 billion position in Wells Fargo.

Is Apple stock still a buy?

Buffett has remained optimistic about Apple stock amid its rapid ascent. Not only is this evident from Berkshire's purchase of 3.9 million more shares during Berkshire's most recently reported quarter, but Buffett also made his bullishness in Apple stock clear in an interview with CNBC this summer. With Apple stock trading above $160 at the time, Buffett said he had personally never sold a single share of the stock -- and it was later revealed that Berkshire's stake in Apple grew further during the quarter that the interview took place.

Apple CEO Tim Cook shakes hands with fans at an Apple store the day of the iPhone 8 launch

Apple CEO Tim Cook at an Apple store. Image source: Apple.

Of course, Apple stock has risen further since this summer and even trades higher than when the third quarter of 2017 ended. Apple stock trades at about $175 per share at the time of this writing. Given Berkshire's slower pace of Apple stock purchases recently compared to 2016 and to the beginning of 2017, Buffett may no longer believe Apple stock is trading at a deep enough discount to be adding meaningfully to the position.

But Berkshire's $23.5 billion wager on Apple stock certainly suggests Buffett believes there's more upside left, even after already making billions of dollars on the investment.