Here's a look at what Warren Buffett's Berkshire has been up to

While some other prominent investors have exited Apple, Warren Buffett's Berkshire Hathaway is increasing its stake in the tech giant.

The Omaha, Neb.-based investing conglomerate owned 15.23 million Apple shares as of June 30, 2016, according to a recent Securities & Exchange Commission filing. That stake, worth $1.46 billion at the time of the filing, is a 55% increase over the 9.81 million shares held in a March 31, 2016 filing.

Earlier this year, Apple stock took a dip when Carl Icahn, who had held 45.8 million shares, valued at about $4.7 billion, sold his shares in the company. Also on Monday, billionaire hedge fund managers Leon Cooperman and George Soros exited Apple with their Omega Advisors and Soros Fund Management selling 227,000 shares and 3,100 shares, respectively.

Shares of Apple (APPL) have risen more than 14% since June 30 to $109.51, which would make the value of Berkshire's Apple stake (if it remains that size) worth about $1.7 billion.

Berkshire also increased its stake in Phillips 66 over the three-month period to 78.8 million shares, up from 75.6 million, or about $6.3 billion.

However, the firm decreased its holdings in retailer Walmart from 55.2 million shares to 40.2 million, or about $2.9 billion.

Berkshire held steady on several stocks including American Express (151.6 million), Coca-Cola (400 million), IBM (81.2 million), Johnson & Johnson (327,100), Kraft Heinz (325.6 million) and Wells Fargo (479.7 million).

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