Although Buffett has been selling Apple stock, it has continued to rise in value this year.Apple (AAPL 0.40%) has been a top Warren Buffett stock for years. The company's strong brand and loyal customer base give it a wide moat, making it relatively easy for the business to grow and become more valuable over the years, which is why Buffett loves the business.But lately, the Oracle of Omaha has been selling shares of the iPhone maker. Apple no longer accounts for close to half of Berkshire Hathaway's portfol ...