McKesson – Goldman Sachs added the health care services company to its "conviction buy" list, saying the Street is not properly appreciating the company's "out sized earnings potential".

EPL Oil & Gas – Energy XXI is buying EPL for $1.5 billion in cash and stock, plus some assumed debt. Energy XXI said the combination will create the only pure-play oil and gas company focusing on the shallower waters of the Gulf of Mexico.

AIG – Deutsche Bank downgraded the insurer's stock to "hold" from "buy", saying elevated expenses may impact AIG's profitability.

Check out which companies are making headlines before the bell:

Express –The retailer reported fourth quarter profit of 57 cents per share, missing estimates by two cents, with revenue also below consensus. The company said it is "disappointed" with its results, citing a heavier-than-planned pace of promotions as negating a rise in comparable store sales.

Google– The search giant will have a double-entry in the S&P 500 following the upcoming creation of a second class of Google stock. S&P reversed an earlier decision to drop one of the Google entries from the index, meaning that although it will still have 500 companies, it will actually contain 501 stocks.

General Mills –The food producer raised its quarterly dividend by eight percent, to 41 cents per share from 38 cents.

Rite-Aid–Goldman upgraded the drug store chain's shares to "buy" from "neutral", saying store remodeling gives Rite-Aid more upside potential, despite an 80 percent run-up since September.

Vornado Realty Trust–Vornado is considering spinning off its suburban strip shopping centers, according to a Dow Jones report. The spinoff could be valued at up to $3 billion.

VeriFone Systems–VeriFone reported a fiscal first quarter profit of 31 cents per share, excluding certain items, four cents above estimates, with revenue also beating consensus. The maker of card-payment systems is also predicting current quarter earnings that are roughly in line with Street estimates.

Diamond Foods–The nuts and snacks producer earned 9 cents per share, excluding certain items, for its fiscal second quarter, beating estimates by a penny. Revenue also came in above Street forecasts, despite a decline in sales of nuts. Diamond is also expecting what it calls "further headwinds" for the nuts segment later in the year.

Herbalife–The nutrition company issued a response to investor Bill Ackman's latest attack on the company focused on its business in China. Herbalife said it remains confident in its business in China, and that its practices in that country are lawful, contrary to Ackman's accusations.

Tesla–The electric car guru will no longer sell its vehicles directly to consumers in New Jersey, after the state voted to prevent Tesla from bypassing franchised dealers.

Men's Wearhouse–The company posted a fourth quarter loss of 38 cents per share, wider than the 13 cent loss expected by Wall Street, with sales also falling below estimates. The stock rose Tuesday following news that the clothing retailer had struck a deal to buy rival Jos. A. Bank in a $1.8 billion deal.

Vimpelcom–Vimpelcom said it is being investigated by the Securities and Exchange Commission, as well as Dutch authorities. The Russian mobile phone operator said the probe was probably in connection with its Uzbekistan operations.

—By CNBC's Peter Schacknow

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