Warren Buffett's Berkshire Hathaway lost more than $3.5 billion on Friday as Apple's stock headed for its worst day on Wall Street in more than four years.

Apple — which posted its fifth consecutive week of losses for the first time since 2012 on Friday — finished the day down 6.6 percent, its worst one-day move since January 2014. The Oracle of Omaha owned more than 250 million shares of the Cupertino, California-based company as reported in Berkshire's latest holdings filing at the Securities and Exchange Commission.

At Friday's closing price for Apple of $207.48, Buffett is down $3.7 billion. The company closed at $222.22 on Thursday before the disappointing report.

Apple's stock sank after the company's iPhone shipments for last quarter fell short of analyst expectations. The company also issued a financial outlook for the rest of the year that underwhelmed some investors. Those factors foiled the company's stronger-than-expected earnings and revenue.

However, Buffett's losses are likely even more painful: he told CNBC at the end of August that he bought more Apple shares since the end of June, when he reported that he bumped his stake up by 5 percent.

"We bought just a little [more]," he said about two months ago on CNBC in an interview with Becky Quick.