Here are five things you must know for Monday, Sept. 18:

1. -- U.S. stock futures were higher on Monday, Sept. 18, after the Dow Jones Industrial Average posted its best week of the year, rising 2.2%.

The blue chip index will begin trading on Monday at 22,268, after ending trading on Friday, Sept. 15 with its fourth straight record close. The S&P 500 closed above 2,500 for the first time on Friday, gaining 0.2% to a record 2,500.23.

Global shares also traded higher on Monday ahead of this week's policy meeting of the Federal Reserve and Donald Trump's speech Tuesday, Sept. 19, at the U.N. Investors will be closely listening to any mention Trump makes about military options on North Korea following the rogue nation's latest missile launch. 

Oil prices in the U.S. early Monday were up 0.2% to $49.90 a barrel. Prices were higher even amid reports that Royal Dutch Shell PLC  (RDS.A)  wasre-starting a key Houston refinery that was shuttered by Hurricane Harvey three weeks ago.

The economic calendar in the U.S. on Monday includes the The National Association of Home Builders Index for September at 10 a.m. ET.

Earnings reports are expected Monday from Steelcase Inc. (SCS) - Get Report .

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2. -- Northrop Grumman Corp. (NOC) - Get Report agreed to buy Orbital ATK Inc. (OA) , a merger that brings together two major U.S. defense contractors, for about $7.8 billion in cash.

The deal also includes the assumption of $1.4 billion in net debt.

Orbital ATK shareholders will receive all-cash consideration of $134.50 a share.

Shares of Orbital closed Friday at $110.04.

The companies expect the transaction to close in the first half of 2018.

Orbital ATK makes missiles and rockets. Northrop Grumman is the fifth-largest defense contractor in the world.

3. -- After the personal information of an estimated 143 million Americans was accessed by hackers targeting Equifax Inc. (EFX) - Get Report , the company's chief information officer and chief security officer are stepping down.

Equifax, the consumer credit rating agency, said late Friday that Chief Information Officer David Webb and Chief Security Officer Susan Mauldin had departed.

Equifax shares have lost a third of their value since the hack, with Morgan Stanley analyst Jeffrey Goldstein writing that the stock could fall down to $50 a share, well below his current price target of $127.

"This could result in higher compliance costs at best, or nationalization of the credit bureau function at worst," Goldstein wrote. "We believe that the sharp price decline over the past few days is related to the steady drumbeat of legislative inquiries, and a lack of clarity on what this means for EFX's future business model. The ultra-bear case that we have heard is that the government could decide to take over the function of the credit bureaus."

4. -- Slack Technologies Inc. said it raised $250 million from SoftBank Group Corp. (SFTBY) and other investors in its latest funding round, boosting the company's valuation to $5.1 billion, Reuters reported.

The latest round of funding, led by SoftBank through its Vision Fund and joined by Accel and other investors, raised Slack's total funds to $841 million, Slack, the enterprise messaging operator, told Reuters in an emailed statement.

The funding will help Slack run as a cash-generating company and reduce its dependence on outside financing, Slack CEO Stewart Butterfield said.

5. -- Wenner Media LLC, the New York-based publisher, said late Sunday, Sept. 17, that it was exploring strategic options for Rolling Stone magazine to help position the brand for future growth.

Wenner sold Us Weekly in March to American Media, publisher of the National Enquirer and Star magazines, for a reported $100 million, as the publisher owned by Jann Wenner contends with falling advertising revenue and as more readers get content online.

The iconic music magazine has evolved over the past 50 years into a multi-platform content brand which reaches more than 60 million people per month. Over the past three years, the brand's digital traffic has grown nearly 50%, its social media presence has grown more than 100% and its monthly video views have gained more than 700%.

Updated from 5:40 a.m. ET.

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