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Here are five things you must know for Wednesday, Dec. 19:

1. -- Stocks Rise Ahead of Fed's Interest Rates Decision

U.S. stock futures traded higher on Wednesday, Dec. 19, as investors prepped for an announcement from the Federal Reserve on interest rates that comes amid increasing concerns of a global economic slowdown.

Contracts tied to the Dow Jones Industrial Average rose 157 points, futures for the S&P 500 rose 16 points, and Nasdaq futures gained 34.25 points. Stocks finished Tuesday, Dec. 18, with slight gains after crude oil fell to its lowest price since August 2017 and sank shares of energy companies.

The Fed is widely expected to lift the range of its key fed funds rate by 25 basis points to 2.25% to 2.5%, according to CME Group futures prices, but may drop its reference to the need for "further gradual rate increases" in 2019 as it monitors data both at home and aboard.

If the central bank does raise rates - the announcement is expected at 2 p.m. ET - it would be the fourth hike this year. But perhaps more importantly, investors will be keying on statements from Fed Chairman Jerome Powell following the rates decision on whether the central bank will stick with projections for three additional rate hikes in 2019.

According to Daniela Mardarovici, a portfolio manager of Bank of Montreal's $1 billion BMO TCH Core Plus Bond Fund, the Fed may scrap its recent pledge to continue raising rates at a gradual pace, while also flagging the increasingly challenging "financial conditions" in global markets.

The economic calendar in the U.S. on Wednesday also includes Existing Home Sales for November at 10 a.m., and Oil Inventories for the week ended Dec. 14, at 10:30 a.m.

General Mills Inc. (GIS - Get Report)  posted adjusted earnings in its fiscal second quarter of 85 cents a share, beating estimates by 4 cents. Revenue of $4.41 billion missed forecasts of $4.51 billion. The stock rose 4.2% in premarket trading.

Earnings reports are expected Wednesday from Rite Aid Corp. (RAD - Get Report) , Pier 1 Imports Inc. (PIR - Get Report)  and Paychex Inc. (PAYX - Get Report) .

2. -- Micron Tumbles on Weak Sales Forecast

Micron Technology Inc. (MU - Get Report)  tumbled 8.4% in premarket trading after the chipmaker beat fiscal first-quarter earnings expectations but missed on revenue, and cautioned that a glut in global semiconductor supplies, along with slowing smartphone demand, would hit second-quarter profit.

Adjusted earnings in the first quarter were $2.97 a share, beating Wall Street's expectations by 2 cents. Revenue of $7.91 billion was below estimates of $8 billion.

Micron said second-quarter sales would slump to between $5.7 billion and $6.3 billion, below consensus of $7.26 billion, and noted that gross margins would narrow to between 50% and 53%.

"We're just going through an air pocket here related to primarily inventory adjustments as well as some seasonal, weak mobile demand, including mobile demand on the high end smartphones that is impacting some of our near-term visibility as well as the near-term outlook," CEO Sanjay Mehrotra told investors on a conference call late Tuesday.

3. -- GlaxoSmithKline and Pfizer Combine Consumer Health Businesses

GlaxoSmithKline PLC  (GSK - Get Report)  said Wednesday it would combine its consumer health division with that of U.S. rival Pfizer Inc.  (PFE - Get Report) to create a new division with $13 billion in annual sales.

GlaxoSmithKline also said it would split its remaining pharmaceutical business into two separate divisions, one focused on over-the-counter drugs, the other on prescriptions and vaccines, following the joint venture creation with Pfizer. GlaxoSmithKline will also own 68% of the newly created group and has another £1 billion in divestments planned over the near term.

"The combination of GSK and Pfizer's consumer healthcare businesses will create substantial further value for shareholders," said GlaxoSmithKline CEO Emma Walmsley. "At the same time, incremental cash flows and visibility of the intended separation will help support GSK's future capital planning and further investment in our pharmaceuticals pipeline."

Pfizer said the deal would add $650 million in cost synergies and add to the company's bottom line for the first three years of the formation. The company also said it would deconsolidate its healthcare business from quarterly and annual earnings once the transaction closes next year.

4. -- FedEx Slumps After Slashing Its Outlook

FedEx Corp. (FDX - Get Report)  fell 8% after the shipping giant's fiscal second-quarter earnings beat expectations but the company lowered its outlook and said its international business "weakened" during the quarter.

FedEx earned an adjusted $4.03 a share in the quarter, higher than Wall Street estimates of $3.94. Revenue of $17.8 billion met forecasts.

"While the U.S. economy remains solid, our international business weakened during the quarter, especially in Europe. We are taking action to mitigate the impact of this trend through new cost-reduction initiatives," CEO Frederick W. Smith said in a statement.

To cut costs, FedEx said it would be instituting buyouts, with costs of $450 million to $575 million expected in the fourth quarter of fiscal 2019. The company said that "similar programs are being considered for employees in international regions." FedEx said it also would be reducing its international network capacity at FedEx Express.

FedEx said it expects adjusted earnings in fiscal 2019 of between $12.65 to $13.40 a share before certain year-end retirement plan accounting adjustments, down from a previous forecast of $15.85 to $16.45 a share.

5. -- Facebook Gave Big Tech Companies More Data Than It Disclosed - Report

Facebook Inc. (FB - Get Report) for years gave some of the world's largest technology companies, like Microsoft Corp. (MSFT - Get Report) and Amazon.com Inc. (AMZN - Get Report) , more intrusive access to users' personal data than it has disclosed, effectively exempting those business partners from its usual privacy rules, The New York Times reported, citing internal records and interviews.

The special arrangements were detailed in hundreds of pages of Facebook documents obtained by the Times. 

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