Stocks: 5 things to know before the open

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It's a big day for big tech companies.

Here are the five things you need to know before the opening bell rings in New York:

1. Big tech gets a boost: Shares in Apple (AAPL) are expected to jump at the open after the company posted the biggest profit in corporate history in the last quarter, when it sold 74.5 million iPhones.

Apple's earnings are helping ARM Holdings (ARMH) in London, a company that sells chip designs to Apple and other smartphone makers. Shares in ARM were rising by 2% in London.

Yahoo (YHOO) shares are also expected to soar at the open after the company said it would spin off its remaining stake in Chinese e-retailer Alibaba (BABA). The deal is expected to save shareholders $16 billion in tax, according to Yahoo CEO Marissa Mayer.

Related: CNNMoney's Tech30

2. Greek stocks and bonds plunge: Greek markets plunged again, with banks suffering the most, after the country's new anti-austerity government was reported to have canceled a planned privatization -- one condition of its international bailout. The benchmark Athens index has now fallen nearly 10% already this year.

The yield on Greece 10-year government bonds jumped 60 basis points to more than 10%.

European markets were mostly weaker, while Asian markets ended mixed.

3. Tech results lift Nasdaq: The tech-heavy Nasdaq index is rising by about 1% premarket as it gets a lift from Apple and Yahoo.

Futures for the Dow Jones industrial average are relatively flat. The S&P 500 is bumping around.

Tuesday was a down day in the markets.

The Dow Jones industrial average plunged by 291 points, while the S&P 500 lost 1.3% and the Nasdaq shed 1.9%.

Investors were in a selling mood after Microsoft (MSFT), Caterpillar (CAT) and Procter & Gamble (PG) all disappointed heavily with their quarterly results.

4. More earnings: Quarterly results are coming in thick and fast.

Boeing (BA), Hess (HES) and Fiat Chrysler (FCAM) are among the main companies reporting earnings before the opening bell.

Facebook (FB) will report after the close.

Related: Fear & Greed Index

5. Focus on the Fed: At 2 p.m. ET, investors around the world will be focusing on the latest announcements from the U.S. Federal Reserve. The Fed is concluding its two-day meeting Wednesday and investors will be parsing through the Fed's new statement to guess when the central bank may be ready to raise interest rates.

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