Check out the companies making headlines before the bell:

Cal-Maine Foods (CALM) – The nation's largest egg producer posted a quarterly loss of 21 cents per share, compared to consensus estimates of a 3 cents per share profit. Revenue also missed estimates, due in large measure to what the company calls challenging market conditions.

Exxon Mobil (XOM) – Exxon Mobil said its fourth-quarter operating results will decline from a year ago, according to a regulatory filing. Exxon now sees a loss in its chemicals unit and a sharply lower operating profit in refining. The energy giant is due to report fourth-quarter earnings on Jan. 31.

Axon (AAXN) – Axon's already-completed acquisition of rival Vievu is being challenged by the Federal Trade Commission (FTC). The FTC said the deal allowed the maker of Taser stun guns and body camera systems to increase prices substantially.

Bed Bath & Beyond (BBBY) – Bed Bath & Beyond signed a deal to sell about half its real estate to private-equity firm Oak Street Real Estate Capital and then lease it back. The transaction will generate more than $250 million for the troubled home goods retailer.

Boeing (BA) – Boeing's 737 Max jet may face more issues before the grounded jet can return to service, according to multiple reports. The Wall Street Journal said the Federal Aviation Administration may mandate more training for 737 Max pilots, and Boeing has confirmed a New York Times report saying an internal audit uncovered issues with electronic wiring that control the jet's tail. Additionally, the Journal reports Boeing is considering raising new debt, to bolster finances which have been strained by the 737 MAX grounding.

Pier 1 Imports (PIR) – The home goods retailer is planning more store closures and cost cuts, along with plans to cut its debt load, according to a Bloomberg report. The news is set to be announced along with Pier 1's quarterly report on Jan. 8.

Nordstrom (JWN) – The retailer was upgraded to "neutral" from "underweight" at JPMorgan Chase, which cited valuation, while increasing its price target on the stock to $41 per share from $26 a share. JPM points to easier comps and a reduction in top-line headwinds, among other factors.

Alphabet (GOOGL) – Alphabet was upgraded to "buy" from "hold" at Pivotal Research, which expects that the stock will outperform its peers. Pivotal also raised its price target on the Google parent's stock to $1,650 per share from $1,445 a share, noting that the company will find new and expanded revenue streams under new CEO Sundar Pichai.

HP Inc. (HPQ) – Mizuho Financial, Citigroup, and Bank of America have agreed to lend up to $24 billion to Xerox (XRX) for potentially pursuing a takeover of the computer and printer maker. A previous cash and stock bid by Xerox for HP had been rejected.

Citigroup (C) – The bank's stock was added to the Goldman Sachs "Conviction List," on the idea that while the market is overvaluing banks in general, it is undervaluing potential return improvement at both Citi and Bank of America (BAC).

SmileDirectClub (SDC) – The maker of direct-to-consumer teeth-straightening products has launched a line of oral care products that will be available exclusively at Walmart (WMT).