Stock futures turned mixed Monday morning as Warren Buffett's Berkshire Hathaway (BRK.A - Get Report) disclosed a stake in Apple (AAPL - Get Report) worth nearly $900 million.

S&P 500 futures were down 0.02%, Dow Jones Industrial Average futures fell 0.09%, and Nasdaq futures gained 0.06%. 

Berkshire held 9.81 million Apple shares as of March 31, a holding worth $1.07 billion at the time. Apple rose 2% in premarket trading. Apple shares have been under pressure after the tech giant reported its first quarterly sales decline in more than a decade. Berkshire also slightly increased its stake in IBM (IBM - Get Report) .

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Economic conditions in the New York region worsened in May. The Empire State index turned negative with a reading of 9 compared to a positive reading of 9.6 in April. Economists expected a positive reading of 5.8. 

Worries over China's economy, the world's second largest, flared over the weekend after industrial output, retail and investment data each missed estimates. Industrial production in China last momth rose just 6%, slowing from 6.8% growth in March. Weaker auto sales dragged on overall retail sales which climbed 5.1% in April, more than half the pace in March. Private investment in fixed assets grew at its slowest pace since 2012. 

Crude oil jumped above $47 a barrel on Monday after Goldman Sachs said the oil market had flipped to a deficit "much earlier than we expected." Analysts said the market likely corrected in May as sustained strong demand and sharply declining production fueled the deficit. The firm expects crude to reach $50 a barrel in the second half of the year. West Texas Intermediate crude oil was up 2.2% $47.21 a barrel early Monday.

Pfizer (PFE - Get Report)  agreed to acquire Anacor Pharmaceuticals (ANAC) for $99.25 a share, or $5.2 billion in cash. Palo Alto, Calif.-based Anacor currently has its lead product candidate, a topical treatment for eczema named crisaborole, under Food and Drug Administration review. Pfizer expects the deal to close in the third quarter of this year. Anacor shares surged 50% in premarket trading. 

Tribune Publishing (TPUB) surged more than 20% in premarket trading after Gannett (GCI - Get Report) increased its acquisition offer to $15 a share from $12.25. Tribune's board had rejected the initial offer. Gannett, owner of USA Today, said the increased offer "reflects additional analysis of certain information revealed in Tribune's financial statements."