Shares in many big-name companies are set for significant swings Wednesday.
Be ready.
Here are the five things you need to know before the opening bell rings in New York:
1. Stock market movers -- Apple, Twitter, Northrop Grumman, Rite Aid, Starwood Hotels: Shares in Apple (AAPL) are jumping ahead of the open after the company reported strong quarterly results. Apple's profit rose 31% as customers continued to buy more expensive iPhones.
On the other hand, Twitter's (TWTR) stock is set to tumble after the tech firm turned in another disappointing earnings report.
Shares in Northrop Grumman (NOC) are rising by about 9% premarket after the company landed a massive contract with the Pentagon to build its Long Range Strike Bomber. The firm is also reporting earnings ahead of the opening bell.
Rite Aid (RAD) shares are sinking about 7% premarket following a 45% surge on Tuesday triggered by reports that Walgreens (WBA) was planning to buy the company. Walgreens confirmed the $17.2 billion deal after the closing bell.
Walgreens is also set to report earnings before trading begins.
And shares in Starwood Hotels (HOT) could be on the move Wednesday after three Chinese firms were reported to be trying to buy the group, which operates W and Sheraton hotels.
Related: CNNMoney's Tech30 Index
2. Ones to watch -- Volkswagen, IBM: Investors are keeping a close eye on Volkswagen (VLKAY) after the company reported a deep loss in the third quarter because of the group's diesel emissions scandal. Shares are rising about 2% in Europe as investors seem relieved that the losses weren't worse.
IBM (IBM) may remain in the spotlight after the tech giant admitted Tuesday that it is under investigation by the U.S. Securities and Exchange Commission. The SEC is conducting an investigation into certain IBM accounting practices in the U.S., UK and Ireland, but the company wouldn't provide further details.
3. Earnings: There are loads of companies reporting earnings today.
Before the open, we'll hear from firms including Fiat Chrysler (FCAM), Hershey (HSY) and the global food giant Mondelez International (MDLZ).
After the close, GoPro (GPRO), Marriott (MAR) and Yelp (YELP) are reporting.
4. Waiting for the Fed: The Federal Reserve will issue its latest decision on interest rates at 2 p.m. ET.
"A change in policy is not, perhaps, terribly likely," said Paul Donovan, a senior economist at UBS. "A change in the nuance of the statement is perhaps more plausible."
The world is waiting for the Fed to raise rates but it's been holding back over lingering concerns about the strength of the U.S. economy as global growth slows.
5. International market overview: U.S. stock futures are edging higher and European markets are mostly rising in early trading.
However, most Asian stock markets ended the day in the red.
On Tuesday, all markets edged lower. The Dow Jones industrial average dipped 0.2%, the S&P 500 lost 0.3% and the Nasdaq slipped by 0.1%.
