NEW YORK (TheStreet) -- U.S. stock futures were signaling a weaker open Monday as Greek debt worries once again put a damper on investor enthusiasm.

Futures for the

Dow Jones Industrial Average

were falling 39 points, or 57.2 points below fair value, at 12,754. Futures for the

S&P 500

were falling 5.5 points, or 7.7 points below fair value, at 1334, and futures for the

Nasdaq

were sliding 9 points, or 12.5 points below fair value, at 2514.

On Friday, the major U.S. stock indexes finished their second best day of trading this year after investors celebrated an unexpected drop in the unemployment rate to its lowest level in almost three years.

Stock futures were falling Monday amid investor fears that Greece was moving closer to a disorderly default as the March 20 deadline for its €14.5 billion ($19.1 billion) bond repayment approaches.

For Greece to be able to repay this debt, the country must reach a deal with its European partners and the International Monetary Fund to receive its second bailout package of €130 billion ($171 billion). However, the negotiations toward the deal are once again hitting roadblocks, with Greek Prime Minister Lucas Papademos unable to convince party leaders backing the country's coalition government to accept the harsh austerity measures that come with receiving the bailout. The three leaders are opposed to measures including steep wage and pension cuts as well as much more stringent tax enforcement, ahead of an expected general election in April.

With the negotiations making very little headway Monday, German Chancellor Angela Merkel turned up the pressure on Greek political leaders. Speaking in front of a press conference in Paris, she said, "We want Greece to stay in the euro ...

but I want to make clear once again that there can be no deal if the troika proposals are not implemented. They are on the table, time is of the essence. Something needs to happen quickly."

The IMF warns that if the European crisis continues to balloon, the 8.2% economic growth that the organization is predicting for China this year, Asia's key economic growth engine, could end up falling four percentage points.

London's FTSE was slipping 0.3%, and Germany's DAX was falling 0.3%. In Asia, Japan's Nikkei Average closed higher by 1.1%, while Hong Kong's Hang Seng index finished down 0.2%.

In corporate news,

Micron

(MU) - Get Report

appointed Mark Durcan as CEO following the death Friday of Chairman and CEO Steve Appleton in a plane crash. Durcan is the chipmaker's president and chief operating officer. His appointment comes a week after Micron announced he would be stepping down in August.

Appleton, a professional stunt plane pilot and former motocross racer, was the only person in the plane when it crashed at the Boise, Idaho, airport.

Boeing

(BA) - Get Report

has ordered inspections of all 787 Dreamliners already built after discovering a manufacturing error causing delamination on the fuselage.

"There is no short-term safety concern," company spokesman Scott Lefeber said in a statement Sunday, but "we have the issue well defined and are making progress on the repair plan." The new flaw will further delay delivery of Boeing's first passenger jet built mainly of carbon-fiber composites. The new jetliner has already faced more than three years of delays.

Boeing shares were declining 1.8% to $75 in premarket trading Monday.

Amazon

(AMZN) - Get Report

plans to open a retail store in Seattle "within the next few month," according to the blog Good E-Reader, which cited "sources close to the situation." The store would be small, focusing on the sale of Amazon's Kindle e-readers and the Kindle Fire tablet, as well as accessories for the products, according to the blog. The first store would appear in Seattle, the Web site said, where the company has its headquarters. Amazon shares were falling 0.5% to $186.66 in premarket trading on Monday.

Humana

(HUM) - Get Report

, the second-largest Medicare provider, reported that fourth-quarter earnings surged 86% as its membership continued to expand with little use of health benefits. The health insurer reported earnings in line with analyst estimates with profit of $1.20 a share, up from 63 cents a share a year earlier. However, revenue came in lower than expected at $9.06 billion, up 9.4% from the prior year. Analysts polled by Thomson Reuters had expected revenue of $9.24 billion.

Humana shares were dropping 1.2% to $89.

Hasbro

(HAS) - Get Report

, the world's second-largest toymaker, reported disappointing sales after weak post-Thanksgiving demand in North America. The maker of Monopoly board games reported fourth-quarter sales of $1.33 billion, missing estimates of $1.34 billion. However, the toymaker reported earnings slightly better than analysts' expectations. The company reported profits of $1.06 a share, beating average estimate of $1.05.

Competitor

Mattel

(MAT) - Get Report

posted a better-than-expected fourth-quarter profit increase of 14% last week on strong Barbie sales.

Hasbro shares were tumbling 5.5% to $33.89.

Former chairman and chief executive officer of

Nabors Industries

(NBR) - Get Report

, Eugene Isenberg, agreed to terminate his employment pact and waive his claim to a $100 million payment.

Isenberg, who headed the oil drilling company for 25 years before announcing his resignation in October, will continue as chairman through his current term ending in June.

No major U.S. economic announcements were expected on Monday.

March oil futures were falling 86 cents to $96.98 a barrel, while April gold futures were dropping $22 to $1,718.30 an ounce.

The benchmark 10-year Treasury was rising 2/32, diluting yield to 1.921%, while the U.S. dollar index was gaining 0.6% to $79.42.

-- Written by Andrea Tse in New York.

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