Warren Buffet's Berkshire Hathaway (BRK.B 0.18%) (BRK.A -1.16%) just loaded up on more Apple (AAPL -2.51%) stock, according to a SEC filing. Apparently, Berkshire's $1 billion position in the tech giant the company initiated earlier this year wasn't enough.

With Berkshire Hathaway upping its stake in Apple, should individual investors do the same?

Warren Buffett. Image source: The Motley Fool.

Berkshire's $1.7 billion stake in Apple

During Q2, Berkshire Hathaway increased its stake in Apple by 5.42 million shares, or 55%. This brings the company's total Apple shares to 15.2 million. At the end of Berkshire's second quarter, these shares were worth $1.46 billion. Shares are worth closer to $1.7 billion as of Tuesday thanks to the stock's 15% rise since the end of June, driven largely by the company's better-than-expected second-quarter earnings report.

After another significant purchase of Apple stock during Q2, the tech giant is becoming one of Berkshire's largest equity holdings. Berkshire has only 13 equity positions in publicly traded stocks worth more than its Apple stake.

Notably, Berkshire's Apple position is now worth more than its stake in General Motors, which is valued at about $1.6 billion at the time of this writing.

Berkshire first started buying Apple stock in the first quarter of 2016. So this makes two quarters in a row of Apple stock purchases for the company.

It likely wasn't Buffett's decision

Investors should note that Berkshire's move to buy more Apple stock during the second quarter likely wasn't Buffett's decision.

As part of the company's plan to prepare Berkshire for an inevitable future without the famed investor, Buffett has brought on hedge-fund managers Todd Combs and Ted Weschler to begin managing some of the company's money. Buffett has said most of the investments made with $1 billion or less are likely investments by the two new investment managers. And this was the case with the company's Apple investment; Buffett specifically confirmed with The Wall Street Journal in May that Berkshire's nearly $1 billion investment in Apple stock in Q1 was made by one of his lieutenants.

With the company's initial position in Apple stock started by one of Buffett's lieutenants, and not the Oracle of Omaha himself, the second-quarter investment was likely made by the same former hedge fund manager.

While an investment decision made by Buffett himself could carry more weight for investors than one made by one of his lieutenants, it's still notable to see Berkshire upping its stake in the tech giant. Though Buffett's lieutenants may sometimes have different opinions than the CEO, they still share common investment principles, namely a commitment to buying undervalued businesses with the intention of holding for very long periods of time -- usually decades. Further, Berkshire's two quarters in a row of significant purchases of Apple stock suggest the company has a high level of confidence in the investment.

Apple store. Image source: Apple.

It's easy to see why Berkshire likes Apple stock. With a price-to-earnings ratio of under 13, the stock's valuation is wildly conservative. Apple's powerful brand, long history of excellent capital stewardship, and undeniable pricing power easily justify this valuation.

In this case, imitating Berkshire's Apple investment seems to make sense. Sure, Berkshire may have not yet made a name for itself when it comes to tech investments, and Buffett himself may not have made this investment decision, but Apple stock already looked like a no-brainer investment opportunity on its own.