Stocks: Cautious trading day ahead

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NEW YORK (CNNMoney) -- U.S. stocks are gearing up for a cautious open Friday, as investors await the outcome of key Greek debt talks.

S&P 500 (SPX), Dow Jones industrial average (INDU) and Nasdaq (COMP) futures hovered around breakeven ahead of the opening bell. Stock futures indicate the possible direction of the markets when they open at 9:30 a.m. ET.

Still looming large over investors are fears about the European debt crisis, particularly the prospect that Greece may end up defaulting in a disorderly fashion. A deal on restructuring Greek debt remained elusive on Thursday, but talks resume on Friday.

The deal is a key condition for Greece to receive additional bailout funds from the European Union and International Monetary Fund. Without additional financial support, Greece may not be able to make a €14 billion payment it owes on bonds that comes due March 20.

Officials from the IMF, EU and European Central bank, known as the troika, are also in Athens reviewing the nation's finances.

Greek debt talks remain elusive

Investors are also still weighing quarterly results from some of the nation's biggest tech firms, which reported after the bell Thursday. Microsoft (MSFT, Fortune 500), Intel (INTC, Fortune 500) and IBM (IBM, Fortune 500) posted solid fourth-quarter earnings but Google badly missed Wall Street forecasts.

"Google was the biggest disappointment, but I would argue that that's just a temporary phenomenon," said Chip Cobb, senior vice president at Bryn Mawr Trust Asset Management.

Google (GOOG, Fortune 500) shares plunged 7.6% in premarket trading Friday, while IBM and Microsoft both gained more than 2%. Intel shares were up 0.2%.

U.S. stocks advanced Thursday, for a third straight session, thanks to solid gains from financial stocks. Shares of both Bank of America (BAC, Fortune 500) and Morgan Stanley (MS, Fortune 500) gained after the firms released their quarterly results.

World markets: European stocks were mixed in morning trading. Britain's FTSE 100 (UKX) ticked up 0.1%, while the DAX (DAX) in Germany slipped 0.5% and France's CAC 40 (CAC40) fell 0.4%.

Asian markets ended higher. The Shanghai Composite (SHCOMP) climbed 1%, the Hang Seng (HSI) in Hong Kong added 0.8% and Japan's Nikkei (N225) rose 1.5%.

Companies: U.S. markets have more corporate earnings to digest, after Dow component General Electric (GE, Fortune 500) reported its quarterly results Friday morning. The company's earnings just beat forecasts, but GE's shares fell 2.8% in premarket trading, as its revenue fell short of expectations.

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Shares of Apple (AAPL, Fortune 500) edged lower, a day after the tech giant's market cap briefly topped $400 billion.

Shares of Carnival Corp. (CCL), which owns the grounded Italian cruise liner Costa Concordia, remain under pressure. Carnival's stock has shed 7% since the Jan. 13 accident. Shares were down another 3.8% in premarket trading Friday.

Economy: At 10 a.m. ET, investors will get report on existing home sales from the National Association of Realtors. Sales are expected to have risen 2.9% in December, according to a survey of analysts by Briefing.com.

Homes are expected to have sold at an annual rate of 4.55 million, up from a rate of 4.42 million in November.

Currencies and commodities: The dollar rose against the euro, the British pound and the Japanese yen.

Oil for February delivery slipped 61 cents to $99.78 a barrel. Oil for March deliver, which becomes the active contract at the close of trade Friday, 66 cents to $99.90.

Gold futures for February delivery fell $6.10 to $1,648.40 an ounce.

Bonds: The price on the benchmark 10-year U.S. Treasury rose, pushing the yield down to 1.98%.