Stocks making the biggest moves premarket: M, STZ, EGN, GSK, WMT & more

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Macy'sThe retailer earned an adjusted 70 cents per share for the second quarter, topping estimates, with revenue also beating forecasts. Comparable sales posted an unexpected rise of 0.5 percent, compared to forecasts of a 0.9 percent decline. Macy's also raised its full year outlook for revenue, comparable sales, and profits.

Constellation BrandsThe spirits producer is investing $4 billion in Canadian cannabis company Canopy Growth, increasing its ownership stake to 38 percent through the exercise of warrants it holds. Constellation is buying the shares at a 51.2 percent premium to yesterday's closing price.

Energen – Energen will be bought by Diamondback Energy in an all-stock transaction worth about $8.4 billion dollars, excluding debt. Diamondback said the combination of the two energy producers should save at least $3 billion in expenses over time.

GlaxoSmithKline - Glaxo's long-acting monthly injection for HIV treatment proved as effective as standard daily pills in a clinical trial.

Express Scripts – The pharmacy benefits manager is in talks with biotech companies Biomarin Pharmaceuticals, Spark Therapeutics, and Bluebird Bio to distribute new hemophilia therapies, according to a Reuters interview with Chief Medical Officer Steve Miller.

Walmart Walmart will collaborate with comedian Ellen DeGeneres on a new women's fashion line.

Yum China – Yum China is a possible target of a variety of investment firms, including Chinese investment firm Hillhouse Capital, according to a Reuters report. Yum China shares had risen four percent yesterday on a Bloomberg report that China Investment Corp. and others were interested in the restaurant operator.

BlackRock - Soros Fund Management significantly boosted its stake in the asset management firm during the second quarter, according to an SEC filing. The fund's BlackRock stake increased by nearly 60 percent to about 13 thousand shares.

Lockheed Martin – The defense contractor was awarded an U.S. Air Force contract for three missile warning satellites, worth up to $2.9 billion.

Berkshire Hathaway – Berkshire increased its stakes in Goldman Sachs, Teva Pharmaceutical, and Apple during the second quarter, according its quarterly SEC filing.

Sears Holdings - CEO Edward Lampert offered to buy the retailer's Kenmore brand for $400 million in cash, according to a letter from Lampert to the Sears board seen by the Wall Street Journal.

Nvidia - Nvidia was upgraded to "outperform" from "underperform" at Wells Fargo, ahead of the chip maker's quarterly earnings report on Thursday. Wells Fargo expects a positive report but said the upgrade also reflects the company's long-term position in gaming, data centers, and autonomous vehicles.

Agilent Technologies Agilent beat estimates by four cents with adjusted quarterly profit of 67 cents per share, while the life science company's revenue matched Street forecasts.

Western Digital – Cowen downgraded the hard disk drive maker to "market perform" from "outperform", saying Street estimates for Western Digital are too high due to competitive pricing in the industry and a cost structure for the company that is not as efficient as those of its rivals.

CORRECTION: This story has been updated to reflect that Macy's EPS came in at 70 cents.