Warren Buffett's sizable holdings in Apple Inc. (AAPL) - Get Report have taken a sizable hit in the last week, with his massive stake going from being worth about $21.3 billion on Sept. 18 to $20.0 billion just a week later. Apple shares have dropped about 6% since then on concerns about sales of the latest iPhones and Apple Watch.

The Oracle of Omaha probably isn't too worried about the decline, given his focus on long-term investing, but $1.3 billion is still $1.3 billion, even to someone who's currently worth more than $78 billion.

The Berkshire Hathaway CEO, who's famously avoided tech companies in the past, first revealed his company's stake in Apple in the first half of 2016 when shares were trading just above $100. He ended 2016 with 59 million shares and more than doubled that to 133 million shares in early January of this year, giving Berkshire about 2.5% of Apple's outstanding shares.

Buffett has said in the past that he believes Apple will be the first company to achieve a $1 trillion market cap. He might need to wait a little bit longer for that to happen, though -- at its current price of $150.75, Apple's market cap is about $778 billion, down from a peak of $846 billion at the beginning of September.

Here's your complete guide to living like Warren Buffett.

Apple is a holding in Jim Cramer'sAction Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells AAPL? Learn more now.

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