Here are five things you must know for Thursday, Aug. 15: 

1. -- Stock Futures Turn Lower After China Threatens Countermeasures if U.S. Levies Tariffs 

U.S. stock futures turned lower Thursday after China says it will retaliate if the U.S. applies tariffs to more China-made goods on Sept. 1.

Stock futures had been pointing higher earlier, a day after the Dow Jones Industrial Average suffered its biggest one-day drop of the year as bond markets flashed warning signs of a recession.

Contracts tied to the Dow fell 78 points, futures for the S&P 500 slipped 5.20 points, and Nasdaq futures were down 35.75 points.

Stocks tumbled Wednesday in the worst day of 2019 after the first inverted U.S. yield curve in more than 12 years stoked fears of a global recession. The Dow finished down 800 points, or 3.1%, to 25,479. The S&P 500 dropped 2.9% and the Nasdaq sank 3%. The Dow and the S&P 500 both closed at two-month lows.

On Wednesday, the yield on the 10-year Treasury fell below that of the two-year for the first time since 2007. The "inverted yield curve" has signaled nearly every U.S. recession for the past 60 years.

"The continued plunge in interest rates, coupled with the ongoing deterioration in global leading economic indicators and (Wednesday's) long-anticipated inversion in the Treasury yield curve, are all proving too much for increasingly wary investors to ignore as the odds of a recession mount," said Alec Young, managing director of global markets research at FTSE Russell.

The two-year Treasury was yielding 1.555% early Thursday while the 10-year was at 1.566%.

Denting market sentiment Thursday was a statement from China's Finance Ministry that said China would take "necessary action" to counter the U.S. decision to apply tariffs to $300 billion worth of China-made goods, some of which will go into effect on Sept. 1.

The economic calendar in the U.S. Thursday includes weekly Jobless Claims at 8:30 a.m. ET, the Philadelphia Fed Business Outlook Survey for August at 8:30 a.m., Retail Sales for July at 8:30 a.m. and Industrial Production for July at 9:15 a.m.

Earnings reports are expected Thursday from Walmart (WMT) - Get Report , Nvidia (NVDA) - Get Report , Alibaba (BABA) - Get Report , Applied Materials (AMAT) - Get Report , Nio (NIO) - Get Report , J.C. Penney JCP, iHeartMedia (IHRT) - Get Report and Tapestry (TPR) - Get Report .

Nvidia is a holding in Jim Cramer's Action Alerts PLUS member club. Want to be alerted before Jim Cramer buys or sells NVDA? Learn more now.

2. -- Cisco Slumps on Weak Outlook

Cisco Systems (CSCO) - Get Report   fell 7.47% to $46.83 in premarket trading Thursday after the networking giant posted fiscal fourth-quarter earnings that topped analysts' estimates but issued a tepid outlook for the first quarter.

Cisco earned 83 cents a share in its fourth quarter, 1 cent better than estimates, on revenue of $13.4 billion that matched forecasts.

Cisco's closely watched product orders were flat during the quarter. Enterprise orders dropped 2%, and service provider orders fell 21%.

Chief Financial Officer Kelly Kramer said on the company's earnings call that Cisco's Chinese product orders fell more than 25%. China accounts for less than 3% of Cisco's revenue but CEO Chuck Robbins said, "It's a small part of our business, but obviously when it falls very dramatically, it can have some impact, because it's greater than zero."

For the first quarter, Cisco said it expects to earn 80 cents to 82 cents a share, compared with analysts' expectations of 83 cents. Revenue was seen between flat and up 2% year over year, or between $13.07 billion and $13.33 billion. Analysts had been calling for revenue of $13.4 billion.

"Weaker-than-expected sales guidance was far from what we had hoped for and it will spook many investors out of CSCO, as well as other technology names on Thursday," said Jim Cramer and the Action Alerts PLUS team, which holds Cisco in its portfolio. "With a market fixated on Treasury yields and an inverted-yield curve (whether it is for the right or wrong reasons as we detailed in Wednesday's members-only conference call) we fully expect some choppiness Thursday."

3. -- Canopy Growth Misses on Revenue, Sinking Shares

Canopy Growth (CGC) - Get Report  was down more than 10% in premarket trading to $28.70 after the largest cannabis company in Canada posted a fiscal first-quarter loss of C$1.28 billion ($960 million), or C$3.70 a share, on revenue of C$90.5 million that missed analysts' forecasts.

The latest quarter included a charge of C$1.2 billion related to the expiration of warrants held by Constellation Brands (STZ) - Get Report , which owns about 38% of Canopy Growth.

Analysts had expected Canopy Growth to post revenue in the period of C$122 million.

Canopy Growth recorded Canadian recreational business-to-business of C$50.4 million. It sold 10 metric tons of cannabis in the fiscal first quarter, up 13% from the fourth quarter.

4. -- Pivotal Software Soars After VMware Makes Buyout Offer

Shares of Pivotal Software  (PVTL) - Get Report jumped more than 67% in premarket trading Thursday after it was disclosed that VMware  (VMW) - Get Reportwas in talks to acquire all of its Class A shares for $15 each.

Pivotal closed Wednesday at $8.30 but was soaring early Thursday to $13.90.

In a Securities and Exchange Commission filing, Dell Technologies Inc. (DELL) - Get Report said special committees of the boards of VMware and Pivotal "are proceeding to negotiate definitive agreements with respect to a transaction to acquire all of the outstanding shares of Class A common stock of Pivotal for cash at a per share price equal to $15."

Dell, which controls both Pivotal and VMware, said in the filing that it was in discussions with VMware as well to determine an exchange ratio to convert all the Class B shares of Pivotal it holds to Class A shares.

Michael S. Dell and Dell Technologies hold 131,306,110 Class B shares of Pivotal. Dell owns 81% of VMware's outstanding common shares

In a statement, VMware confirmed talks were underway, but said it would have no further comment unless and until an agreement is reached.

5. -- Warren Buffett Boosts His Stake in Amazon 

Warren Buffett's Berkshire Hathaway  (BRK.A) - Get Report  lifted its stake in Amazon.com (AMZN) - Get Report , disclosing in a regulatory filing that it owned 537,300 shares of the online retailing giant as of the end of the second quarter, up from 483,300 shares.

The stake is worth $947 million. 

Buffett first revealed in May that Berkshire Hathaway held a stake in Amazon, but said at the time that one of the company's two other investment managers made the pick.

Meanwhile, billionaire investor William Ackman's hedge fund, Pershing Square Capital Management, disclosed that it owned 3.51 million shares of Berkshire Hathaway's B shares as of June 30.

The new stake will be a passive investment for Ackman's firm.

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