Here are five things you must know for Tuesday, Oct. 2:

1. -- Stocks Weaker Amid Growth and Trade Concerns

U.S. stock futures fell on Tuesday, Oct. 2, and global stocks traded mostly lower, with investors citing concerns over prospects for global growth amid lingering trade tensions between the U.S. and China and as the bullish sentiment from the revamp of NAFTA began to fade.

Lost among the trade-related headlines on Monday, Oct. 1, was a low-key warning from International Monetary Fund Managing Director Christine Lagarde, who hinted to an audience in Washington that the IMF is likely to lower its global growth forecast this month amid the U.S.-China trade war, rising interest rates and a stronger U.S. dollar.

"In July, we projected 3.9% global growth for 2018 and 2019," Lagarde said. "The outlook has since become less bright, as you will see from our updated forecast next week."

The new USMCA trade deal, which replaces NAFTA with some specific yet potentially notable changes in the automotive and dairy industries, could also embolden the White House's stance in its current standoff with Beijing, which currently includes tariffs on $250 billion worth of China-made goods and could add levies on a further $267 billion more before the end of the year

Contracts tied to the Dow Jones Industrial Average  fell 86 points, futures for the S&P 500  declined 7.50 points, and Nasdaq futures were down 32.75 points.

2. -- Fed's Powell to Speak, PepsiCo Reports Earnings

The economic calendar in the U.S. on Tuesday includes a speech from Federal Reserve Chairman Jerome Powell at the 60th Annual National Association for Business Economics Annual Meeting in Boston at 12 p.m. ET.

PepsiCo Inc. (PEP)  topped analysts' third-quarter earnings forecasts but trimmed full-year earnings guidance thanks in part to a stronger U.S. dollar.

Pepsi said adjusted earnings in the quarter were $1.59 a share, 2 cents ahead of estimates. Revenue of $16.49 billion also beat forecasts. However, Pepsi shaved a few pennies from its full-year earnings forecast, saying it expects $5.65 a share, narrowly shy of the $5.69 consensus. The company raised its growth outlook for organic revenue. Shares fell slightly in premarket trading.

Automakers, including Ford Motor Co. (F) , will report car sales for September throughout the day.

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3. -- United Technologies Gets U.S. Approval to Buy Rockwell Collins

United Technologies Corp. (UTX) received approval from the Justice Department to buy Rockwell Collins Inc. (COL)  as long as the aerospace and industrial company unloads two Rockwell Collins divisions.

United Technologies will have to sell off Rockwell Collins' pneumatic ice protections business, and its trimmable horizontal stabilizer actuators business.

The $23 billion deal received antitrust approval from the European Union in May. United Technologies expects China to approve the deal once the Justice Department signs off on it.

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4. -- Google's Ad Chief Is Leaving

Sridhar Ramaswamy, who had led Google's online advertising business for the past five years, will be stepping down.

Ramaswamy will be taking a new role at venture-capital firm Greylock Partners, the investment firm said on Monday. In an email to The Wall Street Journal, a Google spokeswoman confirmed the move.

Ramaswamy will be replaced by Prabhakar Raghavan, who has most recently led Google's suite of productivity apps, including Docs, Drive and Gmail, the Journal reported.

The digital-ad business for Google, a unit of Alphabet Inc. (GOOGL) , remains the company's core business. The ads comprise more than 85% of Alphabet's revenue, according to the Journal.

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5. -- Instagram Names a New Boss

Facebook Inc. (FB)  named Adam Mosseri to lead Instagram, just a week after its co-founders said they would be leaving the company.

Instagram co-founders Kevin Systrom and Mike Krieger abruptly announced last week they were leaving the Facebook-owned social media platform, one of Facebook's biggest growth engines

"We are thrilled to hand over the reins to a product leader with a strong design background and a focus on craft and simplicity -- as well as a deep understanding of the importance of community," Systrom and Krieger said in a statement.

Mosseri most recently was Instagram's head of product and previously ran Instagram's news feed. For the short time that Instagram was without a chief, Mosseri had been the favorite to land the position.

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